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Why I can't Convert this string to Double?
bbwolf
2002-07-13 12:01:07
The string is "12.5%"
but I can't Convert it to 0.125
Who can tell me why?
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Why I can't Convert this string to Double?
The string is "12.5%" but I can't Convert it to 0.125 Who can tell me why?
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forestwind
2002-07-13
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说的对
hbxtx
2002-07-13
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自己写个函数,先从字符串中取出12.5,再除以100。
xdev
2002-07-13
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%不是一个数值字符啊
12.5% 要转换位0.125就可以了
chen_funer
2002-07-13
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bbwolf
2002-07-13
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各位的方法我当然是知道的,只是C#中的System.Globalization.NumberStyles.AllowTrailingSign是允许后缀的,
同时ystem.Globalization.NumberFormatInfo.InvariantInfo.PercentSymbol
表示后缀的许可字符,可以将数字转换为包含System.Globalization.NumberFormatInfo.InvariantInfo.PercentSymbol的string.为什么没有反向的?各位不觉得奇怪么?
zyongcai
2002-07-13
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首先要先取出12.5这个字符串,转化成数字,再除以100即可,代码如下:
string a="12.5%";
a=a.Substring (0,a.Length -1);
double b=Convert.ToDouble (a);
MessageBox.Show (b.ToString ());
Sakemail
SakEmail components Copyright ?1997 - 2003 Sergio A. Kessler web: http://groups.yahoo.com/group/sakemail/To subscribe to the mailing list of sakemail, just go tohttp://groups.yahoo.com/group/sakemail/History:0.9 - First released version0.9.1b -Fixed when a mail server reply on the connection with more than one line0.9.2b - I forget to return a value in functions retrieveHeader/Message =) and fixed it. Some minor bugs that I don‘t remember fixed.- Added MIME-compliant base64 support (not for use by now). Added examples.0.9.2.1b- Fixed a bug when send a mail and the first line disappear (thanks to Arun)- Now, you could do MySMTP.MsgTo := ‘a@doma.com; b@domb.com;c@domc.com‘; the spaces before/after semicolon doesn‘t matter (I hope ;)).0.9.3b- Many changes, I added a SakMsg component that make send binary attachments a snap. But have one problem, if you send as attach a file > 20 Kb, it doesn‘t work (I don‘t know why, maybe a problem of sockets). Developed with a version 2.0b of WSockets and D3.0.9.3.1b- Changed the POP.login to a function that return the number of new msgs.- Added the event OnRetrieveProgress on the SakPOP, and fixed the example, sorry =)- Minor changes to the code.1.0- Developed with WSockets 1.2 POP.Login now return a boolean depending id the user is authorized, and POP.Init return the number of new msgs.1.01- Fixed a bug with a bounced mail.1.02- Minor bugs fixed (some variants of boundary)14/10/971.1.0- Warning: WSockets1.2 have some bugs that result in bad attachments. So I decided to use the sockets of Delphi 3 founded in D3 c/s D3.01 pro and D3.01 c/s. Now all seems to work fine and much more smooth. And of course the interface of SakEmail hasn‘t changed.26/10/971.2.0- Added the Reply-To field to TSakMsg comp. Now you must use ‘,‘ when you want to send the msg. to multiple recipients, i.e.: ‘a@doma.com, b@domb.com,c@domc.com‘ This change is done for better compatibility with other emails clients.- Better formatting of the field Date of TSakMsg. Some changes to the code.17/11/971.2.1- Now, all searches are made in case-insensitive, it could prevent some unexpected responses (no one reported, but...). Some changes to the code (again).20/11/971.2.2- Some bugs fixed. (Thanks to Serge Wagener from .lu)24/11/971.2.3- Added the field ‘MIME-Version: 1.0‘. It seems that is necessary :)25/11/971.3.0- Added compatibility with SCO and VAX servers. Fixed a minor bug with the boundary.- Change the generator of the message id.- Added the field MessageId and InReplyTo to the TSakMsg component.- Added the field In-Reply-To that is added to the message generated when it is <> ‘‘.30/11/971.3.1- Almost rewrote the parsing code. Now is more easy for you if you want hack/modify the code.- Better treatment of emails with html inside.15/12/971.4- Added support for UUCoded attachments.- Added a small delay when sending the email, seems that some servers can‘t deglut the info too fast, causing problems with sockets buffers and leading to crash the client machine, I don‘t know if is a Borland bug or Microsoft bug. (thanks to Don Higgins).19/12/971.4.1- Fixed a bug that send
double
‘<‘ and ‘>‘ (ie. <
>) when the full user name is used. Check the new SMTP demo. Thanks to Serge Wagener for locate this bug, track it down and send me the fix.2/2/981.5.0- Added the Canceled property to TSakPOP and to TSakSMTP. Due to this addition now RetrieveAllMessages is a function that return the number of msgs. retrieved and SendMessage is a boolean function (maybe someone has pressed the cancel btn).- Fixed a bug when the subject field is too large.9/2/981.5.1- Fixed a bug with a message within a message (recursive msgs).18/2/981.5.2- Fixed a bug what happens when after the field ‘To:‘ appear a blank line(Thanks to Osvaldo Fillia). Fixed a bug when sending email to more than two address (the separator is still ‘,‘).9/3/981.6.0- Sometimes the filenames of an attachment contain invalid chars making very dificult to open a TSaveDialog (you have noted this ?), now SakEmail deletes the invalid chars.- Applied a patch from Matjaz Bravc, that resolve the problem of localized dates, letting you choose (in design time) if you want localized dates (NOT recommended) or standards dates (english) via the LocalizedDates boolean property in the TSakSMTP comp. Thanks also to Serge Dosyukov for sending me a fix.- Also I applied another patch of Gregor Duchalski that cure a bug with PChar when this unit is used under NT. - It seems that some machines need more delay when sendig a msg (see previous posting 19/12/97), thanks to Matjaz Bravc.- I discover a bug in the transparency code, it is fixed now. Did you see the benefits of Open Source Software ? :)26/3/981.6.1- Added a FUNCFileName private variable to manage the complete path of the attached file. I receive problems reports with this, it work now ?.- Reduced the line sleep to 30 (tell me if this value doesn‘t work for you).27/4/981.7.0- Fixed a memory leak, thanks to Don Higgins.- Moved the
string
esErrorInFormatOfMsg to a property of SakPOP.- Because some people need to use IP addresses instead of Host names, I‘ve added a new property IPAddress to SakPOP and SakSMTP. If both are filled, then the Host name will be used, thanks to Roger F. Reghin for reporting this. The side effect for this is that YOUR app must check if the host is a host name or a IP address, in my app I remove the periods and try to
convert
the result to a float (long integers don‘t work, but float accept chars ‘e‘) if it doesn‘t work I assume that is a host name (someone has a better and simple idea ?).- Added the property FileStream to the class TAtachedFile and the procedure SaveToStream, this was done by Brian Sheperd- The address separator (in the TO: field) is ‘,‘ and ‘;‘ now (before it was ‘,‘ only).1.7.1- Roger F. Reghin has sended me a pair of nice patches that resolve in a good behavior when the destination address is something like "Roger Reghin"
and some servers says that they couldn‘t relay that mail, etc. Also Roger has made the IPAddress property obsolete (do not use it, use Host instead), SakEmail will resolve the host properly no matter if it is a host name or a IP address. So in the next version I will remove the IPAddress property. Thank you, Roger.1.8.0- Well, it seems that I made a mistake, I investigated the previous behavior and it is a fault of the SMTP (RFC 821), so I fixed it.- The IPAddress property has been removed, use Host. Goeran Strehl (asem) has sended me a patch that fix a memory leak and one problem with the object inspector and the Text property of a SakMsg. Dmitry Bondarenko say that some servers do not send the msg size after the RETR command, so he fix that issuing a LIST n command first (work nicely).- Added the property CC (Carbon Copy) to the SakMsg object.1.8.1- Added the property ReturnPath to the SakMsg comp. Minor changes to the scanning code for the filename of attachments.1.8.2- Fixed a bug with the filename of attachments (thanks to Taufer Pavel Ing.).- Added the function IsIPAddress from hou yg (the actual code don‘t work if the server is 265.net :) Fixed a minor bug with html pages like attachments. Some fucking email server return a bounded message declaring the boundary like ‘boundary = ‘ and not ‘boundary=‘ wich is clear in the RFC, fixed.1.8.3- A obscure bug was found by HuangYeJun from china, in the RetrieveHeaders function if the retrieved text was larger than 1024 bytes and the crlf.crlf fall in the middle of two chunks, the function is blocked. I don‘t use this function, btw.1.8.3.1- Just cleaned up a bit the FindUUAtachs function. Not bug or enhancements release. Serge Wagener put me to work >:|1.8.4- Dmitry Bondarenko (again) has found a bug in wich I do not respect the RFC, wich say that replys from the SMTP server could be multi-line, and the previous version just manage as far as two lines. He also send me a nice patch, so the bug is fixed.- Craig Manley added a ExtraHeaders property, please, use with care, it‘s just not valid to put inside it whatever thing.- The CC header was not being added to the headers that were being sent, so Craig fixed it.- Warning: I‘ve put try/except in the TSakPOP.Connect and TSMTP.Connect function around the line FSocket.Open, so you will need to write something like: myPOP.Connect; if POPError then ... in your code, the old way was: try myPOP.Connect; except ..... end; If you are strongly opossed to this change, drop me a line and tell me why (I‘m in doubts).1.8.5- Greg Nixon added the priority property. The default priority for each msg created will be prNormal, so you don‘t need to change your code any bit.1.8.6- Ulf Sturegren has added D4 compatibility, not many changes to the source (one letter), but he found the error.- Hou yg has sent to me a revisited IsIPAddress function, so I put the newer function in, infortunely my reply to him doesn‘t want to go.1.8.7- Ok, I discovered a weird bug, some old emailers (navigator 2) does not format the message in multipart mode if people send an attach, without writing any text and with no MIME settings. Fixed. This could be serious, I recommend upgrading.1.8.8- A small fix with the CC field. Some stupid mail servers put tabs in some fields (CC:, TO:) when they want to make a new line, the correct is to put at least a space in the beginning of the line, added a little code to "fix" that.1.8.9- Some ‘moderns‘ pop3 servers doesn‘t support the LAST command, so I‘ve added a little code to cope with this and added a boolean property ServerSupportLastCmd. See TSakPOP.Init for more details. Reported by Jan Najvarek.1.9.0- Kaufman Alex has added two properties to the SakMsg object, the ContentType and the Headers property, that should be self explaining (I modified a little the code he sended me, btw).1.9.1- I rewrote and greatly simplified the code that deal with the multiple address in the TO: field and remove some possible bugs in it.1.9.2- Alex discovered and fix a bug when a file attached is not enclosed between quotes, resulting in the filename without the first and last character.1.9.3- Better detection of the boundary in multipart messages. Fixed a bug when the attached file is empty.1.9.4- Chris G黱ther send me *lots* of memory leaks fixes, very good job, Chris. - Some weird PGP messages are now processed well.- Yang Qiandong from china fixed a compiler hint and a warning.- Modified TSakSMTP.FReceiveTextFromSocket as suggested by Greg Nixon.- Dmitry Bondarenko send me a patch that fixes some issues with the LAST command (that some servers don‘t implement) and other patch that fixes a problem when servers add spare words in the tail of the answer.- Some minor changes suggested by Matthew Vincent.- Support for _big_ attachments files (me).- Make the code more modular and simple (still is not very modular).1.10.0- Move some stuff to a sak_util unit.- Support for quoted-printable msgs, thanks to Chris G黱ther.- Fix the BCC field.- New property sakMsg.ContentTransferEncoding.2.0.0- Major reestructure of the files and the source code.- Simplifyied sakPOP3.pas a _lot_- Support encapsulated messages (message/rfc822).- Nested multipart messages are processed fine.- Attachs with quoted-printable are processed fine.- Many bugs fixes.2.0.1- A fiasco, sorry.2.0.2- Fixed a bug in the sak_CleanUpAddress.- Do the rigth job if the ContentType is ‘plain/text‘ and the encoding is base64.- Redone sak_ExtractAddress and sak_ExtractAlias.- New ‘Sender‘ property in SakMsg (normally not used, so do not use it, unless you know what you are doing) ‘Thanks‘ to Alex Kaufman for this.2.0.3- A *severe* bug with multiple addresses was fixed.2.0.4- Fixed bogus Message-number (Message-id is the correct) Thanks to Peter Honan- Added SizeInBytes property to the SakMsg component. (petition of Alex Kaufman)- Fixed a minor bug in TSakPOP.RetrieveHeaders. Fix from Alex.- Added RetrieveMessageOnlyHeaders and - RetrieveAllMessagesOnlyHeaders.2.0.5- Fix when the mail server reply is like
(two cr).- Fix function IsIpAddress.- Both fixes by Alessandro Rossi.2.0.6- Fix a bug in the sak_Base64Decode function when the data to decode is null (I found it in the hard way).- Andy Charalambous make it sure you can send more than one email without disconnecting and connecting again.- And Chris ‘Memory Hunter‘ G黱ther killed some memory leaks (again).2.2.0- the f* sleep line that was bothering us for years is gone, gone, gone. Thanks to Syed Ahmed.- a getUIDL method of SakPOP. Thanks to Alex Kaufman.- a UIDL property on SakMsg. (me)- a SakPOP.GetUIDLsOnRetrieve boolean property (default false) (me)- change some ‘Exception.Create()‘ to ‘raise Exception.Create()‘ Thanks to Anton Saburov.- change SakPOP.Init from function to procedure (me)- new SakPOP.NewMsgsCount property (me)- changed SakPOP.Password to SakPOP.UserPassword (me)- changed SakPOP.ErrorInFormatOfMsg to SakPOP.StrErrorInFormatOfMsg- OnLookup event on SakPOP and SakSMTP. Thanks to Syed Ahmed.- OnConnecting event on SakPOP and SakSMTP (me).- OnReceiveTextFromSocket event on SakPOP and SakSMTP (me). (mostly for debug)- OnSendTextToSocket event on SakPOP and SakSMTP (me). (mostly for debug)- Headers are retrieved without the mail body (ugly bug, fix from Alex Kaufman)2.4.0- I‘ve revamped TSakMsg, many funcionality from SakPOP was moved to SakMsg, where it belongs.- Now SakMsg has a RawMail property wich you may find useful, now you can do: SakMsg1.RawMail.LoadFromFile(‘(uidl).mail‘); SakMsg1.ParseMsg; or SakMsg1.RawMail.LoadFromStream( myStream); SakMsg1.ParseMsg; or SakMsg1.RawMail.SaveToFile( ‘(uidl).mail‘); etc, etc...- Added a property TSakMsg.ClearRawMailAfterParse for memory saving.- the return of the f* sleep line (it causes freezes on winsock 1.1 systems like win95, win98 has winsock 2 so there is no problem if you remove the line)- lost of the DecodeProgess events :( (sorry, I don‘t know how to fit this events on the new SakMsg)2.6.0- the sleep() line is dead, it will never come back. Sending an email is a pleasure now.- SakMsg has a TextEncoding (8Bit, Base64) property, I think this will be useful to people with others charset than iso-8859-1- the base64 routines have been rewritten, they are more OO and faster (they are now in SakMIME.pas).- cosmetic changes all over the place.2.6.1- simplifyed ParseMsg2 a lot, it work better now.- speed up the search for uucoded attachs (the previous search was very dumb)- fixed bug Msg.SizeInBytes always 0- added a couple of Application.ProcessMessages to make the app more responsive.2.6.2- moved some functions from sak_utils to SakMIME.- make const parameters all over the place.- fix the bug that introduces a final crlf in quoted-printable attachs.- fix a division by zero if attached file is 0 bytes long, fixed by Peter Kollanyi.2.6.3- fix a rare bug when the header of a email (more probably a encapsulated one) has first line/s in blank. Easy and innocuous bug.2.6.4- fix the bug that insert the attachs of type text/* on the body of the email.- change the Smtp.SendMessage for Smtp.SendTheMessage to avoid a BCBuilder problem. Both problems reported by Andreas Franzen. SendMessage is still there, but it‘s now deprecated, I will remove it in the future.2.6.5- moved the ParseMsg activation from SakPOP to SakMsg (where it belong), this means that after setting the RawMail property of SakMsg, this does a ParseMsg automatically. before: SakMsg1.RawMail := ... SakMsg1.ParseMsg; now: SakMsg1.RawMail := ... hope I‘m not breaking too much code out there ... :)- some changes in the way attachments are processed (now the html part is separated correctly and images within the html are recognized)- RetrieveMessage() and RetrieveMessageOnlyHeaders() now take an additional parameter, a TSakMsg var, so people can change some parameters before parsing, see the source in SakPOP3.pas (the old way is still supported, but they will be removed in the future)- bug fixes that I do not remember.3.0.0- moved code around.- removed deprecated functions (I told you about this)- new SakAttFile unit.- Base64Encode( AttFile), Base64Decode( AttFile), UUDecode( AttFile) has been moved to the TAtachedFile object, so you can do AttFile.Base64Encode, AttFile.Base64Decode, etc- SakSMTP have lost EncodeStart, EncodeProgess and EncodeEnd events as a consequence of the previous change.- SakPOP.Canceled and SakSMTP.Canceled properties have been made read-only and SakPOP.Cancel and SakSMTP.Cancel procedures (or methods) have been added.- add a SakMsg.FillRawMail method that will fill the RawMail property with a rfc822 message based on the properties of SakMsg.- changed SakSMTP.Quit & SakPOP.Quit to Disconnect- deleted TAttachedFile.FileStream (redundant), use BodyBin- removed the function sak_getTempFileName (as it should no be trusted) use function sak_GetTempPath- the new SakIMAP component !, this make a pleasure to work with incoming emails (as you can have folders, etc). Note: the IMAP component has only been tested with the Uni. of Washington server, but it should work with any *STANDARD COMPLIANT* server. Anyways, the code of this component is very simple, so if you have problems, a look in the source code can enligthen you.3.0.1- fixed a brown paper type of bug.3.0.2- support the case where attachs do not come from files (Lars Karlslund)- minor bugfix in UUDecode function (Lars Karlslund)- if the SakMsg.Username is empty, do a VRFY command at the smtp server to try to get the full user name (sergio)- function TSakIMAP.GetFolderList (Peter Nagel)- function TSakIMAP.GetHierarchyDelim (Peter Nagel)- frustrated intent (ie. commented out) to remove memory leaks in POP, SMTP & IMAP destroy functions (Ronald Moesbergen)3.0.3- actually create (and free) the FolderList in sakIMAP (Neculau Andrei)- try to send the FQDM to the HELO command in SMTP (sergio)- commented out the VRFY command in SakSMTP, and cut the from address in the From field (in SakMsg), so if the username is empty, the SMTP server rewrite the from address in a complete way, with username & full address (sergio)- fix a minor bug in TBase64DecodingStream.Write function (Lars Karlslund)3.4.0- many, many improvements to the IMAP component by Peter Honan (I applied the patch with minor modifications, mainly to respect delphi coding standard, taking out the overloading, the selectFolder function was overcomplicated, etc)- FAQ updated (me)3.4.1- minimize the chance for two temporal messages stored on disk to collide (can be hit in previous versions if you run multiple instances of retrieveMessage at the same time)- FAQ updated.3.4.2- a new sak_CleanUpAddresses() implementation, by Knut Baardsen- better handling for temporal messages, suggested by Andrew- many improvements (including ACL -Access Control List) to the IMAP component by James Chaplin3.4.3- reverted to the old sak_CleanUpAddresses() implementation Knut‘s one is almost rigth, but don‘t let us use addresses without domains- add Headers.Clear before filling headers, by "Antonio Carlos Ribeiro Faria"
3.5.0- add TSakMsg.LoadFromTextFile from Oak Chantosa- big jumbo mambo patch from James Chaplin first patch: 1) Operation timeout - OperationTimeout timeout for non-responding receive operations. 2) Forced abend - ForceAbend method that will disconnect and reset state. 3) Optional folder lists - AvFolderList and AvSUBFolderList provide alternatives to FolderList and SUBFolderList that ensure the lists do not contain inacessible folders ( flagged by the server ). 4) Folder name fix - Provided a function to "fix" folder names before submission. Currently it fixes names containing spaces. second patch: 1) Capability - Ask for server capabilities/extensions. 2) Noop - Basic noop command - updates message counts as well - preferred alternative to status. 3) Status - Explicit status command - generally useful for status of a non-selected mailbox. 4) Fetch - Retrieve message data. 5) FetchBody - Retrieve the body of the message. 6) ExamineFolder - A read-only select command. 7) CloseSelectedFolder - Close the currently selected folder. 8) Idle - RFC2177 extension - not implemented on very many servers. 9) Search - Search based on RFC2066 criteria. 10) UIDSearch - Search based on RFC2066 criteria - results are in UID form. 11) UIDStoreFlags - Store message flags based on UID. 12) UIDFetch - Fetch message data by UID. 13) UIDCopyMessageToFolder - Copy a message by UID. 14) Authenticate - Basic framework. Only plain authentication extension implemented. 15) CloseOnError - A new property that allows the user to turn off the default behaviour of disconnecting from the server when an IMAP error is received 16) Namespace - RFC2342 Namespace query command. 17) ListFullHierarchy - Property which allows a switch between "*" ( default ) or "%" as the wilcard for default folder/list methods. 18) List - Explicit list command in case it is needed. third patch: 1) fix problem with imapd 2001a, reported by Holger Mauermann. 2) remove all warnings.3.5.1- revert change to the base64 encoding routine.3.5.2- changes from James Chaplin: 1) TSakIMAP will now properly process non-numeric UIDs for messages ( there was a sak_StrWord2Int transform being used before - which always produced a 0 value for non-numeric UIDs ). 2) TSakIMAP.RetrieveMessageExt ( private method ) was modified to provide a retrieval by either MsgID or UID. 3) TSakIMAP.RetrieveMessageByUID was modified to use the slightly more efficient TSakIMAP.RetrieveMessageExt(UID) method specified in 2) above. I also made an update to the SakMIME.pas unit. The changes that were implemented are: 1) sak_Base64Encode - a basic Base64 encoder.
String
input and
string
output with the option for CRLF splitting. 2) sak_Base64Decode - a basic Base64 decoder.
String
input and
string
output with a control for CRLF interpretation. 3) sak_Base64Verify - a very basic Base64
string
verifier.3.5.3- robustify and code cleanups by Paul Vernon.3.5.4- access violation fix by Paul Vernon.3.5.5- go back to good old trusty 3.5.23.5.6- this time, all the cleanup & fixes from Paul Vernon seems to work well.3.6.0- Paul Vernon latest minor fixes- added basic SMTP authentication, by Delfi and Antonio Carlos Ribeiro Faria3.6.1- fix a mayor bug when sending to many addresses (by sergio)3.7.0- add full support for html mails, by Paul Vernon. (The TAttachedFile now has an extra boolean property called embedded. This property lets you use the syntax
in your HTML mails)- fix a weird typo for BCC fields- add Content-ID, by alejandro Castro- fix "_" characters in subject, regression fix.- cleanups all around, by Paul Vernon.- SMTP example updated to cope with html emails.**warning** from this version, the html part of mails will not be stored as attachments by default, if you want this behavior, you just do something like: aSakMsg := TSakMsg.Create( self); aSakMsg.HTMLAsAttachment := true; ...3.7.1- fix TSakMsg.PopulateList (Jalin)3.7.2 (codenamed "melissa")- fixed a bug when the Populatelist procedure got re-written in sakMsg. It wasn‘t populating the SendTo field if there was only one e-mail address... (Paul Vernon)3.7.3 - Congratulations to Sergio on the addition to his family. This release was made by Paul Vernon who has temporarily taken over the release functions for the SakMail components whilst Sergio spends time AFK!- The 3.7.2 bug fix added blank entries to the address lists. The PopulateList procedure has been re-written again to hopefully cope with any type of e-mail address formatting.- The SMTP example noted in 3.7.0 actually shipped with this release!3.7.4- Bugfix for detecting UUEncoded mails correctly. Previous versions processed MIME mails with the value ‘begin xyz‘ if it appeared at the beginning of a line as a UUEncoded mail when they should not have.- POP and SMTP connect procedures are now functions. Existing code is unaffected. However, you can now use the following code if (sakPOP.Connect) then begin end;- POP gracefully quits if it receives an error now by calling Disconnect correctly.3.7.5- Further code to improve identification of UUEncoded mails. Essentially looking for the end as well as the beginning to ensure that it is correct.- Code optimisation of certain UUEncoded mail id functions.- Fix to ensure that the body of a mail that is UUEncoded is not lost.- MIME-Version
string
introduced into TsakMsg component to help with UUEncoded mail identification.- SizeInBytes property altered to read private variable using a function. If the private variable is 0, the function reads the length of the FRawMail.Text property.- Fix to make sure that the filename is not overwritten by a blank value when parsing mail-headers.3.7.6- Fixed list index out of bounds error.- Added POP3 RSET call TSakPOP.Reset.3.7.7- Altered SizeInBytes and Octets values to return server-side size when d/l headers only and use actual size once the entire message is downloaded.- Fixed a bug in GetBasicHeaders where To and CC fields could be mishandled if the mail headers were formed in a particular way.4.0.0 beta- All methods are now wrapped in classes. sak_util is now included for backwards compatibility only.- Several changes to make sakMail thread safe including the introduction of Mutexes which are cross process safe. Critical sections were an option however, although mutexes are a little slower, they are much more effective when you aren‘t sure how the code is going to be deployed...- Made several changes to the way connections are tracked, now making better use of the underlying Delphi components own properties and functions.- Several bug fixes included from solutions posted on mailing lists. Including change to datetime function to respect local time separator. There are more including one that Adem re-raised.- Removed almost all pointers as per Adems suggestion. Makes for neater code.- Hopefully backwards compatibility is kept. This is one of the objectives of the excersice although, internally, the components no longer use any of the non-object based methods. Also some of the non-object based methods actually have been re-written to create an object use the instance of the original method and then destroy the object again. This introduces a minor overhead however, because the objects are discreet, the trade is for much better memory usage and greater thread safety.- Introduced an include file to define compiler directives. Currently there are two directives. One defines whether to use the VCL or not, the other defines whether or not to use the Fast
String
s components. - With the intoduction of the Include file, this allows the development of code that is optional for users. One of these such changed is the use of the Fast
String
s base64 decoder. If you install the Fast
String
s components and turn on the compiler directive, you should have no functional changes however, the base64 decoder routines should have a much higher performance rating. Tests clock in at over 2000% faster attachment decoding on a P4 1.8GHz machine. (1.2Mb file 1686mS native sak Base64 Decoder, 79mS using Fast
String
s!)- This version is being released as a beta as the changes are pretty drastic. If the code is deemed to be stable and backwards compatible then it will be re-released as v4.0.1 with no changes.4.0.1 beta- Fixed an issue where Range Checking highlighted that the Attachment b64 decode routine raise a Range Error if the line that was to be decoded was empty. i.e. ‘‘.- Introduced a compiler directive to turn off range checking in the sakMIME procedure TBase64DecodingStream.Write to make sure that it runs correctly as Range Checking causes issues in this function.4.0.2 beta- Changed MailDateToDateTime function to the one provided by DengZhaoHui with a few modifications as even though it has better date processing than the original it caused E
Convert
Errors with some non-rfc dates.- Added the compiler directive to allow the inclusion of MD5 components from the DCPCrypt suite of encryption components. This allows the components to do APOP and SMTP AUTH functions as specified in RFCs 2095, 2104, 2449 and 2554. {UseDCP} ***** NOTE: These functions are experimental as although they are RFC compliant, they have not been tested against a secure mail server yet... *****- Using EurekaLog during load testing of the POP mail component, found and fixed several AV‘s in sakMSG, sakMIME and sakPOP. Mainly simple mistakes that required re-ordering of code or more checks before trying to manipulate data.- Altered the sockets code to be more stable with some servers. The previous implementation was totally incompatible with SendMail NT v3.0.2.- Fix added to compensate for incorrect operation of Connected property in some versions of Delphi.- Altered GetMultiLineFieldBody as per Adems suggestion. Also took some of Adems code and added it to GetFieldValueFromLine as the escape characters can appear in single line headers as well as multi-line ones.- TClientSocket is deprecated in Delphi 7. This may be the next large change in the sakEmail components. - Updated distribution to include more RFC‘s regarding the message format, POP and IMAP and hashing functions for CRAM mechanisms.- Fixed the handling of redirected mails as created by Eudora.- Force PopulateList to clear the list before populating it again.- Created a Delphi 6 package file.4.0.3 - Fixed AUTHSMTP buffer initialisation error. (Dmitry G. Kozhinov and Gabi Slonto)- Improved identification of servers that do not support the UIDL command. A small overhead is intorduced on servers that do support the command and have several mails to download but the feature allows better interaction with those servers that do not support UIDL.- Priority is now reported correctly when an e-mail is being decoded rather than only being used when sending an e-mail.4.0.4- Fixed an issue with a malformed header in a mail sent from MS Word through an Exchange server- Added a couple of try...finally blocks to the sakIMAP component.- Altered the sakIMAP components connected function to mirror the more accurate sakPOP method.- Consolidated all compiler directives into sakDef.inc- Added versioning compiler directives to allow the compilation of sakemail under Delphi 4.- General tidying of code. 4.0.5- Created a Delphi 7 package- Added properties to the IMAP component to allow read access to the LocalAddr and LocalHost socket properties.- Bugfix to sakMsg PopulateList function where a comma separated list did not contain any spaces- Access violation in sakPOP component due to incorrect use of free,freeandnil and compiler directives4.0.6- Added several features to the IMAP components.- Tidied up SMTP authentication routines (Improved use of MD5 for authentication using DCP components)- Included capability to send messages without an SMTP server (using Indy DNS components for MX lookups)- Bugfix in message parsing to stop a recursion loop due to a malformed mail.4.0.7- Memory leaks found by Amos and Paul regarding the sakMsg and sakPOP units respectively.- Bug fixes to attachment save code including stripping out invalid .. sequences from filenames- Improved the GetConnectedState method to check against the RemoteHost value on the Socket.- Updated POP example to be more responsive when downloading mail. Fixed a memory leak.Don‘t forget to subscribe to the mailing list (see the web pages at http://groups.yahoo.com/group/sakemail/)
UE(官方下载)
Keyboard shortcuts A quick reference guide to UltraEdit's default keyboard shortcuts Keymapping and custom hotkeys How to customize 键映射s and menu hotkeys Column Markers The benefit of a column maker is that it can help you to format your text/code, or in some cases to make it easier to read in complex nested logic. Quick Open UltraEdit and UEStudio provide multiple methods to quickly open files without using the standard Open File dialog. A favorite method among power users is the Quick Open in the File menu. The benefit of the quick open dialog is that it loads up very... Vertical & Horizontal Split Window This is a convenient feature when you're manually comparing files, when you want to copy/paste between multiple files, or when you simply want to divide up your edit space. Tabbed Child Windows Declutter your edit space by using the tabbed child windows feature Auto-Hide Child Windows When you're deep in your code, the most important thing is editing space. The all new auto-hide child windows give you The all new auto-hide child windows allow you to maximize your editing space by hiding the child windows against the edge of the editor. Customizing toolbars Did you know that you can not only change what is on UltraEdit's toolbars, you can also change the icon used, as well as create your own custom toolbars and tools? File tabs Understand how file tabs can be displayed, controlled and configured through the window docking system in UltraEdit/UEStudio. Create user/project tools Execute DOS or Windows commands in UltraEdit or UEStudio Temporary Files UltraEdit and UEStudio use temporary files... but what are temporary files? This power tip provides an explanation as well as some tips to get the most out of temp files. Backup and Restore Settings One of the staples of UltraEdit (and UEStudio) is its highly configurable interface and features. However, what happens when you're moving to a new system and you want to port your settings and customizations over along with UltraEdit? Add a webpage to your toolbar Use UltraEdit's powerful user tools to launch your favorite website from the click of a button on your toolbar Integrate Yahoo!, Google, Wikipedia and more with UltraEdit This tutorial will show you how to access the information you need in your browser by simply highlighting your text in the edit window and clicking your toolbar button How to install UE3 UE3 is the portable version of UltraEdit developed specifically for the U3 smart drive. You will need a U3-compatible USB drive for this power tip Scripting tutorial An introduction to UltraEdit's integrated scripting feature The List Lines Containing
String
option in Find The lists lines option can be a handy tool when searching because it presents all occurrences of the find
string
in a floating dialog box. You can use the dialog to navigate to each instance by
double
-clicking on one of the result lines... Scripting Access to the Clipboard How to access the Clipboard using the integrated scripting engine Scripting access to output window How to access the output window using the integrated scripting engine Writing a macro Steps to record and edit powerful macros to quickly and efficiently edit files Using "copied" and "selected" variables for dynamic macros Use copied and selected text in macros to dramatically increase the power and flexibility of UltraEdit macros Run a macro or script from the command line We are often asked if it is possible to run an UltraEdit macro or script on a file from the command line. The answer is yes - and it's not only possible, it's extremely simple! Using find/replace UltraEdit and UEStudio give you the ability to perform a find or replace through one or more files. Learn how to use UltraEdit/UEStudio's powerful find and replace. Multiline find and replace Search and replace text spanning several lines Incremental search Incremental search is an inline, progressive search that allows you to find matched text as you type, much like Firefox's search feature Regular expressions Regular Expressions are essentially patterns (rather than specific
string
s) that are used with Find/Replace operations. This guide can dramatically improve your speed and efficiency for Find/Replace Tagged expressions "Tagging" the find data allows UltraEdit/UEStudio to re-use the data similar to variable during a replace. For example, If ^(h*o^) ^(f*s^) matches "hello folks", ^2 ^1 would replace it with "folks hello". Perl compatible regular expressions An introduction to using Perl-style regular expressions for search/replace Perl regex tutorial: non-greedy regular expressions Have you ever built a complex Perl-style regular expression, only to find that it matches much more data than you anticipated? If you've ever found yourself pulling your hair out trying to build the perfect regular expression to match the least amoun... Remove blank lines A question we often see is "I have a lot of blank lines in my file and I don't want to go through and manually delete them. Is there an easier way to do this?" The answer is: yes! Configure FTP Set up and configure multiple FTP accounts TaskMatch Environments How to use TaskMatch Environments in UltraEdit and UEStudio Configure FTP backup Save a local copy of your files when you transfer them to FTP directories Encrypt and Decrypt Text Files Use UltraEdit to encrypt and decrypt your text files Link to remote directories Sync local directories with remote (FTP/SFTP) directories Compare Modified File Against Source File How to compare the modified file against the source file on disk. Column Based Find and Replace Need to restrict your search/replace to a specific column range? The column based search does just that... Compare Highlighted Text If you need to quickly compare of portions of text, rather than an entire file, then you need UltraEdit/UEStudio's selected text compare! The selected text compare allows you to select portions of text between 2 files and execute a compare on ONLY the se Using the SSH/telnet console A tutorial for UltraEdit/UEStudio's SSH/telent feature Adding a wordfile Adding a wordfile in UltraEdit v15.00 and greater Adding a wordfile (in v14.20 and earlier) Add a language definition to your wordfile for use with UltraEdit and UEStudio's powerful syntax highlighting Syntax highlighting and code folding Explanation of highlighting and folding definitions in the UltraEdit/UEStudio wordfile Create Your Own TaskMatch Environment How to create your own TaskMatch Environments Filtering the Explorer View How to filter the Explorer view in UltraEdit and UEStudio Group Files and Folders with Projects How to group your files and folders using Projects Adding or removing file extensions for syntax highlighting How to configure syntax highlighting to highlight different file types automatically Project Settings Advanced Project Features - Using the UltraEdit/UEStudio project settings dialog Scripting Techniques Scripting techniques for UltraEdit/UEStudio. Perl-style regular expressions for function
string
s Using Perl-Style regexes to identify functions in your syntax-highlighted files and populate the function list Autocorrect keywords in UltraEdit/UEStudio How to enable and disable autocorrect keywords with syntax highlighting Insert Menu Commands UltraEdit includes several special insert functions under the Insert menu. You can use these functions to insert a file into the active file, insert a
string
into the file at every specified increment, sample colors from anywhere on your screen, and more. Using Bookmarks UltraEdit and UEStudio provide a way for you to mark, access, and preview your favorite lines via bookmarks. We'll look at how to create, edit, and configure bookmarks in the bookmark viewer. Creating Search Favorites UltraEdit includes a Search and Replace Favorites feature that allows you to manage frequently used Find and Replace
string
s. Create, name, and edit your Search and Replace Favorites... Customizing The HTML Toolbar Commands The purpose of this power tip is to teach you how to customize the existing HTML tags and create your own HTML tags. Combine All Open Files into a Single Destination File Have you ever needed to combine multiple files into a single destination (output) file? You can use a combination of a script and tool to create a single file from multiple files. Sum Column/Selection in Column Mode This power tip demonstrates how to calculate the sum from a column of numeric data. Column mode How to use the features of UltraEdit's powerful column mode Advanced and column-based sort How to sort file data using the advanced sort options and the column sort options Working with CSV files Use UltraEdit's built-in handling for character-separated value files Word wrap and tab settings for different file types UltraEdit and UEStudio allow you to customize the word wrap and tab settings for any type of file. This power tip walks you through the steps to configure these customizations Versioned backup Set UltraEdit/UEStudio to automatically save versioned backups of your files Configure spell checker How to set the highly-configurable options for UltraEdit's integrated spell checker Special functions UltraEdit includes several special functions under the File menu. You can use these functions to insert a file into the current file, delete the active file, send the file through email, or insert a
string
into the file at every specified increment HTML preview Edit and preview your rendered HTML code in the edit window Custom templates Create templates for frequently used text. You can also assign hotkeys to your templates. Compare files/folders Integrated differences tool - comparing files and folders with UltraCompare Professional File change polling Monitor log files and more using UltraEdit's file change polling feature Vertically split the edit window Splitting the edit window in UltraEdit/UEStudio Large file text editor UltraEdit can be used to edit large text files. Learn how to configure UltraEdit to optimize editing large text files Multiple configuration environments of Ultraedit/UEstudio How to set up your separate environments for UltraEdit/UEStudio Java compiler Create a custom user tool to compile Java code, using the command line, from within UltraEdit Configure UltraEdit with javascript lint How to check your JavaScript source code for common mistakes without actually running the script or opening the web page Character properties at your fingertips Access the properties of a character with the click of a button Ctags Set up and configure Ctags for use in UltraEdit Visual SourceSafe integration Create a customized user tool to check out files from Visual SourceSafe Running WebFOCUS from UltraEdit Configure UltraEdit for use with WebFOCUS CSE HTML Validator CSE HTML Validator for Windows is the most powerful, easy to use, user configurable, and all-in-one HTML, XHTML, CSS, link, spelling, and accessibility checker available. This quick tutorial shows you how to use it and set it up in UltraEdit/UEStudio Working with Unicode in UltraEdit/UEStudio In this tutorial, we'll cover some of the basics of Unicode-encoded text and Unicode files, and how to view and manipulate it in UltraEdit. Search and delete lines found UEStudio and UltraEdit provide a way for you to search and delete found lines from your files. This short tutorial provides the steps for searching for and deleting lines by writing a simple script. Parsing XML files and editing XML files Parsing XML can be a time-consuming task, especially when large amounts of data are involved. As of v15.10, UltraEdit provides you with a the XML Window for the purpose of parsing your XML files. The XML window allows you to navigate through the XML... Using Bookmarks UltraEdit and UEStudio provide a way for you to mark, access, and preview your favorite lines via bookmarks. We'll look at how to create, edit, and configure bookmarks in the bookmark viewer. Using the CSS style builder UltraEdit and UEStudio both include a CSS style builder for you to easily configure and insert CSS styles into the active document. This power tip will show you how to use the style builder. SSH/Telnet Session Logging Log the input and output to/from the server in your SSH/Telnet sessions Edit, develop, debug, and run SAS programs This user-submitted power tip describes how to use UltraEdit as a SAS editor, as well as how to run and debug SAS programs from the editor itself Tabs to Spaces - Ignore tabs and spaces in
string
and comments Ever had to
convert
the tab characters to spaces, but wanted to leave the tabs in
string
s and comments untouched? In previous versions, the
convert
tabs to spaces feature didn't distinguish between tabs as whitespace/formatting vs. tabs in... Setting File Associations in UltraEdit/UEStudio A file association is used by Windows Explorer to determine which application will open the file when it is
double
-clicked (or opened) in Explorer. In the interest of speed, many UltraEdit/UEStudio users want to associate specific file types with... Windows Explorer Integration We know that many UltraEdit/UEStudio users don't operate solely from within the editor; rather, they are frequently working in Windows Explorer before going to the editor. As such, they want (and need) a quick and easy way to open files from within... Line Change Indicator Ever wanted to see what changes you've made since your last save, or have you ever wanted to know what lines you've changed during an edit session? As of UltraEdit v16.00, you can do just that with the line change indicator... Comment and Uncomment Selected Text How many times per day do you comment out a block of code? Do you ever get tired of manually typing your open and close comments? As of v16.00, simply highlight your code, click a button, and move on. It's that easy... Hide, Show, and Delete Found Lines in UltraEdit/UEStudio Over time, many of our users have asked for the ability to hide/show lines based on a Find
string
... you got it! As of v16.00, you can now hide/show and even delete text based on your search criteria. The following power tip will guide you through... Read Only Status Indicator Have you ever opened a file, tried incessantly to modify it, then realized it was read only? As of v16.00, UltraEdit includes an enhanced read only status indicator. For read only files, the file tab will display a lock icon. Additionally, you can... Regular Expression Builder Regular Expressions are essentially patterns, rather than literal
string
s, that are used to compare/match text in Find/Replace operations. As an example, the * character in a Perl regular expression matches the preceding character or expression zero or.. XML Manager: In-line editing of XML files The XML Manager allows you to navigate through complex XML data. But, what happens when you want to make a quick edit to your XML tags/data.... UltraEdit v16.00 extends the XML Manager with inline editing, giving you a faster and more elegant method... UltraEdit v16.00 Scripting Enhancements One of UltraEdit's trademark features is the ability to automate tasks through scripting. V16.00 extends the power of scripting further with includes, active document index, and more! Parse Source Code with the Function List The function list displays all the functions in the active file/project.
Double
clicking on a function name in the list repositions the file to the desired function. Also, as you navigate through a file, the function selected in the list changes to indica Brace Matching Brace matching is an often-used feature; it is indispensable for navigating through your code. Brace matching simply allows you to position your cursor next to an open (or close) brace and highlight the corresponding brace. Code Folding Code folding is indispensable for managing complex/nested code structures. Code folding allows you to collapse (hide) a section of code. The collapsible sections are based on the structure of the file/language Shared FTP accounts Do you use multiple IDM products - UltraEdit, UEStudio, or UltraCompare? Ever get sick of managing your FTP account information in each application? Now you can stop worrying about porting your FTP account settings! Simply configure it once and share you Auto-load macro with project Many UltraEdit/UEStudio users rely heavily on projects - and why not, projects are extremely helpful in managing related files and folder. Projects not only allow you to group/manage your files and folders, but projects also contain other items that... UEStudio 使用技巧 Using the classviewer A tour of UEStudio's classviewer which provides a parsed graphical representation of your project CVS/SVN Auto-Detect UEStudio can automatically detect and import your CVS/SVN account settings when you import a folder already under version control. IntelliTips UEStudio offers language intelligence in an exciting feature we call IntelliTips (like Intellisense). Imagine a function parameter list tooltip coupled with an intelligent auto complete tooltip for code elements of the current file Quickstart guide: Using UEStudio to develop Java applications A guide for using UEStudio to edit and develop Java applications Create a local PHP MySQL development environment How to set up a development environment for PHP/MySQL on your local machine. A development environment allows you to test your code as you develop your web application before publishing it to the web. Quickstart Guide: Using UEStudio with Borland C/C++ Compiler C/C++ developers can use UEStudio to set up and configure projects with the Borland C/C++ compiler Creating your first application Create, build, and run an application from within UEStudio Configuring VCS with UEStudio A guide for configuring version control support (VCS) in UEStudio 11 and later Configuring VCS with UEStudio (in v10.30 and earlier) A guide for configuring version control support (VCS) in UEStudio CVS Diff How to use the built-in CVS Diff commands with UEStudio and UltraCompare Add a file to version control system A trademark feature of UEStudio is it's powerful Version Control System. As you continue in your development, it is likely you will need to add files to the version control repository Compare files/folders A guide for comparing files or folders from UEStudio using the integrated diff tool Quickstart guide: Using the integrated debugger A guide for setting up integrated WinDbg debugging in UEStudio Quickstart guide: Using the integrated PHP debugger A guide for setting up the integrated PHP debugger in UEStudio Using the SSH/telnet console A guide for setting up SSH/telnet in UEStudio Keymapping and custom hotkeys A guide for customizing 键映射, menus and menu hotkeys in UEStudio Configuring SVN and CVS Accounts A cornerstone feature of UEStudio is the version control support. UEStudio supports CVS and SVN as well as multiple connection protocols. Before you can use version control, you must create an account. UEStudio has an auto-detect CVS/SVN feature, but... Group Files and Folders with Projects How to group your files and folders using Projects UltraEdit for Linux 使用技巧 FTP through Nautilus Did you know that you can access remote FTP files in UltraEdit for Linux with a variety of server connection protocols? Using Nautilus, the default file manager for the popular GNOME desktop, you can access files via FTP, SFTP, Windows shares, or even... Primary Select Using Linux's primary select feature in UltraEdit for Linux Custom terminal Set up a user tool to interact with the command line and specify a custom terminal for output Custom file browser UltraEdit for Linux allows you to right-click any file or folder in your Project (from the File View) and browse it on the file system. But did you know that you can configure which file browser is launched from UltraEdit? Scripting tutorial An introduction to the integrated scripting feature in UltraEdit for Linux Writing a macro Steps to record and edit powerful macros to quickly and efficiently edit files Vertical and horizontal split window editing This is a convenient feature when you're manually comparing files, when you want to copy/paste between multiple files, or when you simply want to divide up your edit space. Find and Replace A guide to the powerful features and options available under the "Search" menu. Find in Selected Text Find and Replace is a cornerstone feature for UltraEdit, so it is of course integral to UltraEdit for Linux. The Linux version offers the same features as in the Windows version, as well as additional features. One specific feature that was improved... Using bookmarks Provides a way for you to mark and quickly access lines of interest in your files via bookmarks. To add a bookmark, make sure the cursor is positioned on the line you'd like to bookmark. Press CTRL + F2.... Adding a wordfile Add a language definition to your wordfile for use with UltraEdit's powerful syntax highlighting Projects In UltraEdit for Linux, projects are a convenient, time-saving, feature that allow you to group and manage associated files. Additionally, Projects are integrated throughout the framework of UltraEdit making it easier to perform other actions on your... Search Favorites UltraEdit for Linux includes a Search and Replace Favorites feature that allows you to manage frequently used Find and Replace
string
s. Create, name, and edit your Search and Replace Favorites... Column mode How to use column and block selection mode in UltraEdit for Linux Templates How to create text editing templates in UltraEdit for Linux Keyboard shortcuts A quick reference guide to UltraEdit's (Linux) default keyboard shortcuts How to use the UltraEdit for Linux tar package This guide shows you how to download and use the tar.gz package of UltraEdit UltraEdit for Linux v1.20: Scripting enhancements One of UEx's trademark features is the ability to automate tasks through scripting; v1.2 extends the power of scripting further with includes. UltraEdit for Linux Command Line Support UltraEdit for Linux has many convenient command line options and flags for calling UEx from a console/terminal as part of a script, or simply for convenience. Advanced file sorting Sort files in UEx with a powerful array of options and settings, including optional sort keys UltraCompare 使用技巧 Compare text snippets A tutorial showing you how to compare text snippets without having to save your snippets into a file. Diff your snippets, merge your changes, save the result as a separate file, then clear out the snippets (and their temp files...) Increase your virtual memory Large file comparisons may require your system to use virtual memory. This tutorial shows you how to configure Windows to increase the amount of virtual memory on your system. Compare large files UltraCompare is a very robust file comparison tool which includes support for comparing large files even several GB large. This power tip shows you how to optimize UltraCompare for maximum performance when working with large files. Compare .zip, .rar., and .jar Archives Got Archives? UltraCompare's archive compare feature allows you to compare the contents of .zip files, .rar files, Java .jar files, and even password-protected .zip files. Use the archive compare and examine differences between archives or folders on th Version Control Comparison UltraCompare v6.40 includes major improvements to the command line support that allow greater flexibility when integrating with other applications. If you're using version control in a team development environment, then UltraCompare v6.40 is exactly... Visually inspect HTML code How to use UltraCompare Professional's integrated browser view to visually compare and inspect HTML code Compare directories using FTP/SFTP Configure FTP/SFTP accounts in UltraCompare Professional to backup or sync FTP directories and compare local and remote folders. Block and line mode merge Merge differences and save them between 2 or 3 files at the click of a button Sync files and folders with the Folder Synchronization feature Folder Synchronization is a powerful feature in UltraCompare which allows you to sync files between local, remote, network, and even FTP folders. Recursive compare Use recursive compare to evaluate subdirectories' content for differences Find and eliminate duplicate files Unnecessary and unwanted duplicate files can eat up valuable system disk space. This power tip will show you how to quickly and safely eliminate unwanted duplicate files from your system with the powerful Find Duplicates feature in UltraCompare Compare Word documents Compare multiple Microsoft Word documents - Identify and merge differences between Word documents. Command line tips Tips for running UltraCompare from a DOS command prompt Command line quick difference check Run a quick difference check between two files to quickly see if they're the same or different Ignore options Setting ignore options for file/folder comparisons in UltraCompare Ignore/compare column range Set parameters to ignore or compare up to 4 unique columns of data. Filtering files in folder mode Filtering files in UltraCompare while in folder mode Customizing the time/date format for folder comparison Many UltraCompare users in different regions of the world have different standard formats for dates and timestamps. UltraCompare provides the ability to customize the date and timestamp for your folder comparisons Editing files in UltraCompare How to use the integrated text editing capabilites within UltraCompare UltraCompare shell integration Tips for integrating UltraCompare into the right-click context menu in Windows Explorer Export/save text compare output How to export and save diff output from UltraCompare Web Compare If you work with web files, you are probably accustomed to downloading the file via FTP or viewing the source, saving the text, then doing a compare. We're sure you'll agree, this process is clunky and mechanical.... Manually Sync Your Compare Manually sync your compare lines UltraCompare Sessions If you're anything like us, you always have multiple applications running at once. Spawning multiple instances of any application makes it harder to work. So... UC gives you sessions to manage your compare operations! Customizing colors Tutorial on how to change the colors for folder/file compare in UltraCompare Reload previously active sessions When you're doing complex file and folder compare operations, it doesn't take long to open quite a few tabs. What happens when you close UC to move on to another task or to go home for the day- lose the session? Not with Reload active sessions... Session Manager If you've compared the same set of files/folders more than once... You need sessions. Sessions allow you to save compare options for a common set of files or folders which you can quickly recall anytime you open UltraCompare. Not only can you save... Workspace Manager The Workspace Manager is all about convenience, so the Explorer view allows you to drag/drop files and folders for quick and easy compare operations. Simply select the folder (or file) in the Explorer view and drag it to the compare frame. Bookmark Favorite Files/Folders in UltraCompare How to use Favorite in UltraCompare to bookmark your commonly used files/folders. FTP in Workspace Manager You can access your accounts through the Explorer tab of the Workspace Manager in UltraCompare Share FTP Accounts with UltraEdit/UEStudio Set up UltraEdit/UEStudio to share FTP accounts with UltraCompare FTP Folder Compare with CRC Have you wanted to do a quick folder compare - between a local directory and remote directory - without downloading the files first? No problem... As of v7.20, UltraCompare now supports an FTP CRC compare method. With the CRC compare feature... Mark and hide files and folders in folder compare Have you ever wanted to hide files/folders that aren't relevant for your immediate compare needs? We have... While UltraCompare offers many compare filters and ignore options, sometimes you just need more control... UltraSentry 使用技巧 Web browser cleanup Use UltraSentry to securely clean up history and temporary files associated with web browsers Application Cleaning Support Clean the sensitive data left behind after running your applications Delete browser cookies Protect your privacy and your security by securely deleting malicious or private cookies Download directory cleanup Securely delete your download history with UltraSentry Optimize your browser Using UltraSentry to improve speed, performance, and security of your browser Explorer/Microsoft office Integration Tips for integrating UltraSentry into the right-click context menu in Windows Explorer or MS Office Stealth mode Tutorial for running UltraSentry in the background or system tray Scheduling a task Tutorial for scheduling UltraSentry to automatically execute a specific cleaning task Run UltraSentry as a system service How to Schedule your profiles/cleaning operations and be sure that UltraSentry is running them whether you are logged in or not Using the Wizard UltraSentry's wizard makes secure/privacy cleaning operations quick and easy. This power tip shows you how to use the wizard. Total System Scrub Information on how to use UltraSentry's "Full System Scrub" profile to protect your privacy and secure your sensitive data Custom profiles This power tip describes how to set up your own custom profile so that you can securely clean only areas of the system that you wish to clean Securely delete email How to securely delete email on your system using UltraSentry Advanced features This power tip describes some of the advanced features and functionality of UltraSentry
Using LUA with Visual C++ (Introduction)
What is LUA? LUA is a scripting language, its power lies in the fact that it can be embedded in your C++ programs. Scripts give you the possibility to change the behaviour of your C++ programs without any need to recompile your program. A real world example would be game programming: you only have to change the script(s) and you can create a whole new game using the same engine. LUA is fully customizable, you can create your own script functions and expose them to a 3th party. Or you can create scripts, encrypt them and then decrypt them at run-time so that only a number of limited people can script for your program. Allowing the end-user to modify your program, gives your program a point ahead to the competition. Using LUA in your program does require some thinking ahead... You have to choose what kind of functions you allow in the scripts. For example: a function savegame would be logic and usefull and so could be a function deletesavegame but making a function such as deletefile public can be dangerous. The LUA version discussed is 5.0.2. Don't forget that this document is only a quick introduction and that it is not a complete tutorial about LUA. How to embed LAU into C++? Another way to formulate this question : "How can I use LUA in my Visual C++ Project?". The answer is actually pretty easy, you download it from lua.org and you follow the instructions below. Know that there are several ways to add LUA to your project and I only explain one of them. NOTE: I'm assuming that you know the basics about how to use your compiler, the instructions outlined below are ment for Microsoft Visual C++ 6. Installation : dowload LUA here (links to official website) Extract the files to a folder, for example "c:\Program Files\LUA SDK" Configuration : In your Microsoft Visual C++ IDE Go to Tools->Options. Select Directories and add the LUA include-directory. Add LUA to your project (non-MFC) : Create a new folder in your project's workspace and call it LUA. Add the files. Select and insert all the files in the LUA src-directory (from lapi.c to lzio.h). Add LUA to your project (MFC) : Create a new folder in your project's workspace and call it LUA. Add the files. Select and insert all the files in the LUA src-directory (from lapi.c to lzio.h). MFC uses precompiled headers, LUA doesn't, so let's disable them. Select the LUA folder in your workspace and press the right mouse button, then select Settings from the menu. Select "All Configurations". Then open the LUA folder and select all the .c-files (make sure your selection doesn't include a folder or a .h file!). On the right side a C++-tab will appear. In that C++-tab select the "Precompiled Headers"-catagory. And select "Not using precompiled headers". Press the OK-button to finish. About ANSI C and C++ LUA is pure ANSI C code, this means that if you build the code with a C++ compiler it will complain with "error LNK2001: unresolved external symbol" messages. Two easy ways exist to resolve this problem without modifying the original source files : Tell the compiler that the function definitions are C style by enclosing the include directive with the extern keyword : extern "C" { #include
} You can also define LUA_API before including lua.h : #define LUA_API extern "C" #include
I recommend that you use the first method. The LUA State In order to use LUA you have to initialize it and when you're done with it you have to deinitialize LUA. This is done by respectivily opening and closing an LUA state. // Open the LUA state lua_State *L = lua_open(); // Use LUA... ; // Close the LUA state lua_close(L); You can have multiple LUA states in your program which are all indepedent of each other. The LUA Stack LUA is stack-based. The communication between the script and the C/C++ application happens between a stack maintained by LUA. Note that each LUA state has its own stack. A clean programmer will ensure that the stack is zero at the end of his program. You can verify this by calling the lua_gettop function, the result must be zero, it's a good candidate for the _ASSERT macro (defined in crtdbg.h). // Open the LUA state lua_State *L = lua_open(); // Use LUA... ; // Verify the stack // (don't forget to include crtdbg.h) _ASSERT(lua_gettop(L) == 0); // Close the LUA state lua_close(L); LUA defines lua_pushXXX (where XXX can be "
string
", "number", "boolean", ...) but it doesn't define the lua_popXXX versions. Here's an example how to define them by yourself : inline LUA_API lua_Number lua_popnumber(lua_State *L) { register lua_Number tmp = lua_tonumber(L, lua_gettop(L)); lua_pop(L, 1); return tmp; } inline LUA_API const char *lua_pop
string
(lua_State *L) { register const char *tmp = lua_to
string
(L, lua_gettop(L)); lua_pop(L, 1); return tmp; } When popping the values they are
convert
ed automaticly when possible : // Push -1 as a number lua_pushnumber(L, -1); // And pop it again as a
string
(s --> "-1") const char *s = lua_pop
string
(L); If the conversion is impossible then NULL/0 will be returned. For example we can't
convert
a boolean to a
string
: // Push 1 (true) lua_pushboolean(L, 1); // And pop it again as a
string
(s --> NULL) const char *s = lua_pop
string
(L); There are many other stack manipulation functions and there are also functions to verify the value type on the stack. I suggest that you check out the LUA manual that comes with the distribution. Executing an LUA script Executing an LUA script isn't that straight-forward at first but at the end it turns out the be very simple. I'm explaining you the full implementation of how to execute a script by creating your own "reader". LUA comes with its own library that contains ready-to-use functions but I prefer you to explain the complete version so you can understand better how LUA works. In order to execute LUA scripts you have to load them first and call them afterwarts, this is done by respectivily calling the lua_load and the lua_call or lua_pcall function. The lua_load function takes four parameters : LUA_API int lua_load (lua_State *L, lua_Chunkreader reader, void *data, const char *chunkname); The first one is the pointer to the LUA state, the second one is a pointer to a user-defined reader function, the third pointer is a user-defined value that the reader function will receive, and the fourth one is a name we decide ourselves for debugging purposes. As you can see from this call, there is no argument accepting a script. We have to define this ourselves using the data argument. Let's take a look at this structure (taken from the LUA library), we will define : typedef struct luaMemFile { const char *text; size_t size; } luaMemFile; The text variable will be our script line(s) and the size variable will tell us if we have finished reading or not (see later). A value of zero will mean : we are no longer reading. We now define a simple callback function : const char *readMemFile(lua_State *, void *ud, size_t *size) { //
Convert
the ud pointer (UserData) to a pointer of our structure luaMemFile *luaMF = (luaMemFile *) ud; // Are we done? if(luaMF->size == 0) return NULL; // Read everything at once // And set size to zero to tell the next call we're done *size = luaMF->size; luaMF->size = 0; // Return a pointer to the readed text return luaMF->text; } Once the script has been loaded, a simple call to lua_pcall will suffice. I prefer lua_pcall above lua_call because the later one will terminate the program if there was an error. The lua_call takes three parameters and the lua_pcall function takes four parameters : LUA_API void lua_call (lua_State *L, int nargs, int nresults); LUA_API int lua_pcall (lua_State *L, int nargs, int nresults, int errfunc); The first parameter is the pointer to the LUA state, the second parameter is the number of arguments on the stack that the command takes (and when executing a loaded script this can remain 0). The third parameter is the number of result parameters the command will return on the stack. If nresult equals LUA_MULTRET then the number of parameters that will be pushed on the stack is controlled by the called function! Yes indeed, an LUA function can return more than one parameter, for example : return "i", "return", 5, "
string
s", "and", 2, "numbers" The fourth parameter (errfunc) is only valid for the lua_pcall function and is used for controlling the error-handling. Please read the LUA manual for more information about this parameter. A note about the nresults argument: if we take the example return statement above, then we see that 7 values would be returned. If we execute this script with nresult==LUA_MULTRET then 7 values would be returned, if we would call the function with nresult==3 then only the 3 first values would be returned ("i", "return" and 5). This is the test script we will execute : const char *testscript = { "function
double
(n)\n" " return n * 2\n" "end\n" "\n" "return
double
(1)\n" }; function
double
(n) return n * 2 end return
double
(1) A quick but nasty way of executing would be this : // luaMemFile luaMF; // Load the command and try to execute it... luaMF.text = testscript; luaMF.size = strlen(luaMF.text); lua_load(L, readMemFile, &luaMF, "test script"); lua_pcall(L, 0, 0, 0); You may ask why is this a bad method? Well, there is no error checking, if the script contains error or an execution error occur than the stack will be messed-up, LUA functions push their error values on the stack so you need to check the result of both lua_load and lua_pcall and act accordingly! This is the implementation that I prefer : // luaMemFile luaMF; // Load the command and try to execute it... luaMF.text = testscript; luaMF.size = strlen(luaMF.text); if(lua_load(L, readMemFile, &luaMF, "test script") == 0) { // Execute the loaded command... // The function takes 0 parameters and will return 1 result if(lua_pcall(L, 0, 1, 0) == 0) { // There was no error // Let's get the result from the stack lua_Number result = lua_tonumber(L, lua_gettop(L)); } // Clean-up the stack lua_pop(L, 1); } else { // There was a lua_load error... // Pop the error value from the stack lua_pop(L, 1); } Calling C functions from LUA In order to make this topic more accessible, a whole new page has been assigned to it, please follow this link : Calling C functions from LUA or How to expose C function to LUA scripts. 来源: http://www.codegurus.be/codegurus/Programming/luaintroduction_en.htm
Google C++ Style Guide(Google C++编程规范)高清PDF
Table of Contents Header Files The #define Guard Header File Dependencies Inline Functions The -inl.h Files Function Parameter Ordering Names and Order of Includes Scoping Namespaces Nested Classes Nonmember, Static Member, and Global Functions Local Variables Static and Global Variables Classes Doing Work in Constructors Default Constructors Explicit Constructors Copy Constructors Structs vs. Classes Inheritance Multiple Inheritance Interfaces Operator Overloading Access Control Declaration Order Write Short Functions Google-Specific Magic Smart Pointers cpplint Other C++ Features Reference Arguments Function Overloading Default Arguments Variable-Length Arrays and alloca() Friends Exceptions Run-Time Type Information (RTTI) Casting Streams Preincrement and Predecrement Use of const Integer Types 64-bit Portability Preprocessor Macros 0 and NULL sizeof Boost C++0x Naming General Naming Rules File Names Type Names Variable Names Constant Names Function Names Namespace Names Enumerator Names Macro Names Exceptions to Naming Rules Comments Comment Style File Comments Class Comments Function Comments Variable Comments Implementation Comments Punctuation, Spelling and Grammar TODO Comments Deprecation Comments Formatting Line Length Non-ASCII Characters Spaces vs. Tabs Function Declarations and Definitions Function Calls Conditionals Loops and Switch Statements Pointer and Reference Expressions Boolean Expressions Return Values Variable and Array Initialization Preprocessor Directives Class Format Constructor Initializer Lists Namespace Formatting Horizontal Whitespace Vertical Whitespace Exceptions to the Rules Existing Non-conformant Code Windows Code Important Note Displaying Hidden Details in this Guide link ▶This style guide contains many details that are initially hidden from view. They are marked by the triangle icon, which you see here on your left. Click it now. You should see "Hooray" appear below. Hooray! Now you know you can expand points to get more details. Alternatively, there's an "expand all" at the top of this document. Background C++ is the main development language used by many of Google's open-source projects. As every C++ programmer knows, the language has many powerful features, but this power brings with it complexity, which in turn can make code more bug-prone and harder to read and maintain. The goal of this guide is to manage this complexity by describing in detail the dos and don'ts of writing C++ code. These rules exist to keep the code base manageable while still allowing coders to use C++ language features productively. Style, also known as readability, is what we call the conventions that govern our C++ code. The term Style is a bit of a misnomer, since these conventions cover far more than just source file formatting. One way in which we keep the code base manageable is by enforcing consistency. It is very important that any programmer be able to look at another's code and quickly understand it. Maintaining a uniform style and following conventions means that we can more easily use "pattern-matching" to infer what various symbols are and what invariants are true about them. Creating common, required idioms and patterns makes code much easier to understand. In some cases there might be good arguments for changing certain style rules, but we nonetheless keep things as they are in order to preserve consistency. Another issue this guide addresses is that of C++ feature bloat. C++ is a huge language with many advanced features. In some cases we constrain, or even ban, use of certain features. We do this to keep code simple and to avoid the various common errors and problems that these features can cause. This guide lists these features and explains why their use is restricted. Open-source projects developed by Google conform to the requirements in this guide. Note that this guide is not a C++ tutorial: we assume that the reader is familiar with the language. Header Files In general, every .cc file should have an associated .h file. There are some common exceptions, such as unittests and small .cc files containing just a main() function. Correct use of header files can make a huge difference to the readability, size and performance of your code. The following rules will guide you through the various pitfalls of using header files. The #define Guard link ▶All header files should have #define guards to prevent multiple inclusion. The format of the symbol name should be ___H_. To guarantee uniqueness, they should be based on the full path in a project's source tree. For example, the file foo/src/bar/baz.h in project foo should have the following guard: #ifndef FOO_BAR_BAZ_H_ #define FOO_BAR_BAZ_H_ ... #endif // FOO_BAR_BAZ_H_ Header File Dependencies link ▶Don't use an #include when a forward declaration would suffice. When you include a header file you introduce a dependency that will cause your code to be recompiled whenever the header file changes. If your header file includes other header files, any change to those files will cause any code that includes your header to be recompiled. Therefore, we prefer to minimize includes, particularly includes of header files in other header files. You can significantly minimize the number of header files you need to include in your own header files by using forward declarations. For example, if your header file uses the File class in ways that do not require access to the declaration of the File class, your header file can just forward declare class File; instead of having to #include "file/base/file.h". How can we use a class Foo in a header file without access to its definition? We can declare data members of type Foo* or Foo&. We can declare (but not define) functions with arguments, and/or return values, of type Foo. (One exception is if an argument Foo or const Foo& has a non-explicit, one-argument constructor, in which case we need the full definition to support automatic type conversion.) We can declare static data members of type Foo. This is because static data members are defined outside the class definition. On the other hand, you must include the header file for Foo if your class subclasses Foo or has a data member of type Foo. Sometimes it makes sense to have pointer (or better, scoped_ptr) members instead of object members. However, this complicates code readability and imposes a performance penalty, so avoid doing this transformation if the only purpose is to minimize includes in header files. Of course, .cc files typically do require the definitions of the classes they use, and usually have to include several header files. Note: If you use a symbol Foo in your source file, you should bring in a definition for Foo yourself, either via an #include or via a forward declaration. Do not depend on the symbol being brought in transitively via headers not directly included. One exception is if Foo is used in myfile.cc, it's ok to #include (or forward-declare) Foo in myfile.h, instead of myfile.cc. Inline Functions link ▶Define functions inline only when they are small, say, 10 lines or less. Definition: You can declare functions in a way that allows the compiler to expand them inline rather than calling them through the usual function call mechanism. Pros: Inlining a function can generate more efficient object code, as long as the inlined function is small. Feel free to inline accessors and mutators, and other short, performance-critical functions. Cons: Overuse of inlining can actually make programs slower. Depending on a function's size, inlining it can cause the code size to increase or decrease. Inlining a very small accessor function will usually decrease code size while inlining a very large function can dramatically increase code size. On modern processors smaller code usually runs faster due to better use of the instruction cache. Decision: A decent rule of thumb is to not inline a function if it is more than 10 lines long. Beware of destructors, which are often longer than they appear because of implicit member- and base-destructor calls! Another useful rule of thumb: it's typically not cost effective to inline functions with loops or switch statements (unless, in the common case, the loop or switch statement is never executed). It is important to know that functions are not always inlined even if they are declared as such; for example, virtual and recursive functions are not normally inlined. Usually recursive functions should not be inline. The main reason for making a virtual function inline is to place its definition in the class, either for convenience or to document its behavior, e.g., for accessors and mutators. The -inl.h Files link ▶You may use file names with a -inl.h suffix to define complex inline functions when needed. The definition of an inline function needs to be in a header file, so that the compiler has the definition available for inlining at the call sites. However, implementation code properly belongs in .cc files, and we do not like to have much actual code in .h files unless there is a readability or performance advantage. If an inline function definition is short, with very little, if any, logic in it, you should put the code in your .h file. For example, accessors and mutators should certainly be inside a class definition. More complex inline functions may also be put in a .h file for the convenience of the implementer and callers, though if this makes the .h file too unwieldy you can instead put that code in a separate -inl.h file. This separates the implementation from the class definition, while still allowing the implementation to be included where necessary. Another use of -inl.h files is for definitions of function templates. This can be used to keep your template definitions easy to read. Do not forget that a -inl.h file requires a #define guard just like any other header file. Function Parameter Ordering link ▶When defining a function, parameter order is: inputs, then outputs. Parameters to C/C++ functions are either input to the function, output from the function, or both. Input parameters are usually values or const references, while output and input/output parameters will be non-const pointers. When ordering function parameters, put all input-only parameters before any output parameters. In particular, do not add new parameters to the end of the function just because they are new; place new input-only parameters before the output parameters. This is not a hard-and-fast rule. Parameters that are both input and output (often classes/structs) muddy the waters, and, as always, consistency with related functions may require you to bend the rule. Names and Order of Includes link ▶Use standard order for readability and to avoid hidden dependencies: C library, C++ library, other libraries' .h, your project's .h. All of a project's header files should be listed as descentants of the project's source directory without use of UNIX directory shortcuts . (the current directory) or .. (the parent directory). For example, google-awesome-project/src/base/logging.h should be included as #include "base/logging.h" In dir/foo.cc, whose main purpose is to implement or test the stuff in dir2/foo2.h, order your includes as follows: dir2/foo2.h (preferred location — see details below). C system files. C++ system files. Other libraries' .h files. Your project's .h files. The preferred ordering reduces hidden dependencies. We want every header file to be compilable on its own. The easiest way to achieve this is to make sure that every one of them is the first .h file #included in some .cc. dir/foo.cc and dir2/foo2.h are often in the same directory (e.g. base/basictypes_test.cc and base/basictypes.h), but can be in different directories too. Within each section it is nice to order the includes alphabetically. For example, the includes in google-awesome-project/src/foo/internal/fooserver.cc might look like this: #include "foo/public/fooserver.h" // Preferred location. #include #include #include #include #include "base/basictypes.h" #include "base/commandlineflags.h" #include "foo/public/bar.h" Scoping Namespaces link ▶Unnamed namespaces in .cc files are encouraged. With named namespaces, choose the name based on the project, and possibly its path. Do not use a using-directive. Definition: Namespaces subdivide the global scope into distinct, named scopes, and so are useful for preventing name collisions in the global scope. Pros: Namespaces provide a (hierarchical) axis of naming, in addition to the (also hierarchical) name axis provided by classes. For example, if two different projects have a class Foo in the global scope, these symbols may collide at compile time or at runtime. If each project places their code in a namespace, project1::Foo and project2::Foo are now distinct symbols that do not collide. Cons: Namespaces can be confusing, because they provide an additional (hierarchical) axis of naming, in addition to the (also hierarchical) name axis provided by classes. Use of unnamed spaces in header files can easily cause violations of the C++ One Definition Rule (ODR). Decision: Use namespaces according to the policy described below. Unnamed Namespaces Unnamed namespaces are allowed and even encouraged in .cc files, to avoid runtime naming conflicts: namespace { // This is in a .cc file. // The content of a namespace is not indented enum { kUnused, kEOF, kError }; // Commonly used tokens. bool AtEof() { return pos_ == kEOF; } // Uses our namespace's EOF. } // namespace However, file-scope declarations that are associated with a particular class may be declared in that class as types, static data members or static member functions rather than as members of an unnamed namespace. Terminate the unnamed namespace as shown, with a comment // namespace. Do not use unnamed namespaces in .h files. Named Namespaces Named namespaces should be used as follows: Namespaces wrap the entire source file after includes, gflags definitions/declarations, and forward declarations of classes from other namespaces: // In the .h file namespace mynamespace { // All declarations are within the namespace scope. // Notice the lack of indentation. class MyClass { public: ... void Foo(); }; } // namespace mynamespace // In the .cc file namespace mynamespace { // Definition of functions is within scope of the namespace. void MyClass::Foo() { ... } } // namespace mynamespace The typical .cc file might have more complex detail, including the need to reference classes in other namespaces. #include "a.h" DEFINE_bool(someflag, false, "dummy flag"); class C; // Forward declaration of class C in the global namespace. namespace a { class A; } // Forward declaration of a::A. namespace b { ...code for b... // Code goes against the left margin. } // namespace b Do not declare anything in namespace std, not even forward declarations of standard library classes. Declaring entities in namespace std is undefined behavior, i.e., not portable. To declare entities from the standard library, include the appropriate header file. You may not use a using-directive to make all names from a namespace available. // Forbidden -- This pollutes the namespace. using namespace foo; You may use a using-declaration anywhere in a .cc file, and in functions, methods or classes in .h files. // OK in .cc files. // Must be in a function, method or class in .h files. using ::foo::bar; Namespace aliases are allowed anywhere in a .cc file, anywhere inside the named namespace that wraps an entire .h file, and in functions and methods. // Shorten access to some commonly used names in .cc files. namespace fbz = ::foo::bar::baz; // Shorten access to some commonly used names (in a .h file). namespace librarian { // The following alias is available to all files including // this header (in namespace librarian): // alias names should therefore be chosen consistently // within a project. namespace pd_s = ::pipeline_diagnostics::sidetable; inline void my_inline_function() { // namespace alias local to a function (or method). namespace fbz = ::foo::bar::baz; ... } } // namespace librarian Note that an alias in a .h file is visible to everyone #including that file, so public headers (those available outside a project) and headers transitively #included by them, should avoid defining aliases, as part of the general goal of keeping public APIs as small as possible. Nested Classes link ▶Although you may use public nested classes when they are part of an interface, consider a namespace to keep declarations out of the global scope. Definition: A class can define another class within it; this is also called a member class. class Foo { private: // Bar is a member class, nested within Foo. class Bar { ... }; }; Pros: This is useful when the nested (or member) class is only used by the enclosing class; making it a member puts it in the enclosing class scope rather than polluting the outer scope with the class name. Nested classes can be forward declared within the enclosing class and then defined in the .cc file to avoid including the nested class definition in the enclosing class declaration, since the nested class definition is usually only relevant to the implementation. Cons: Nested classes can be forward-declared only within the definition of the enclosing class. Thus, any header file manipulating a Foo::Bar* pointer will have to include the full class declaration for Foo. Decision: Do not make nested classes public unless they are actually part of the interface, e.g., a class that holds a set of options for some method. Nonmember, Static Member, and Global Functions link ▶Prefer nonmember functions within a namespace or static member functions to global functions; use completely global functions rarely. Pros: Nonmember and static member functions can be useful in some situations. Putting nonmember functions in a namespace avoids polluting the global namespace. Cons: Nonmember and static member functions may make more sense as members of a new class, especially if they access external resources or have significant dependencies. Decision: Sometimes it is useful, or even necessary, to define a function not bound to a class instance. Such a function can be either a static member or a nonmember function. Nonmember functions should not depend on external variables, and should nearly always exist in a namespace. Rather than creating classes only to group static member functions which do not share static data, use namespaces instead. Functions defined in the same compilation unit as production classes may introduce unnecessary coupling and link-time dependencies when directly called from other compilation units; static member functions are particularly susceptible to this. Consider extracting a new class, or placing the functions in a namespace possibly in a separate library. If you must define a nonmember function and it is only needed in its .cc file, use an unnamed namespace or static linkage (eg static int Foo() {...}) to limit its scope. Local Variables link ▶Place a function's variables in the narrowest scope possible, and initialize variables in the declaration. C++ allows you to declare variables anywhere in a function. We encourage you to declare them in as local a scope as possible, and as close to the first use as possible. This makes it easier for the reader to find the declaration and see what type the variable is and what it was initialized to. In particular, initialization should be used instead of declaration and assignment, e.g. int i; i = f(); // Bad -- initialization separate from declaration. int j = g(); // Good -- declaration has initialization. Note that gcc implements for (int i = 0; i < 10; ++i) correctly (the scope of i is only the scope of the for loop), so you can then reuse i in another for loop in the same scope. It also correctly scopes declarations in if and while statements, e.g. while (const char* p = strchr(str, '/')) str = p + 1; There is one caveat: if the variable is an object, its constructor is invoked every time it enters scope and is created, and its destructor is invoked every time it goes out of scope. // Inefficient implementation: for (int i = 0; i < 1000000; ++i) { Foo f; // My ctor and dtor get called 1000000 times each. f.DoSomething(i); } It may be more efficient to declare such a variable used in a loop outside that loop: Foo f; // My ctor and dtor get called once each. for (int i = 0; i < 1000000; ++i) { f.DoSomething(i); } Static and Global Variables link ▶Static or global variables of class type are forbidden: they cause hard-to-find bugs due to indeterminate order of construction and destruction. Objects with static storage duration, including global variables, static variables, static class member variables, and function static variables, must be Plain Old Data (POD): only ints, chars, floats, or pointers, or arrays/structs of POD. The order in which class constructors and initializers for static variables are called is only partially specified in C++ and can even change from build to build, which can cause bugs that are difficult to find. Therefore in addition to banning globals of class type, we do not allow static POD variables to be initialized with the result of a function, unless that function (such as getenv(), or getpid()) does not itself depend on any other globals. Likewise, the order in which destructors are called is defined to be the reverse of the order in which the constructors were called. Since constructor order is indeterminate, so is destructor order. For example, at program-end time a static variable might have been destroyed, but code still running -- perhaps in another thread -- tries to access it and fails. Or the destructor for a static '
string
' variable might be run prior to the destructor for another variable that contains a reference to that
string
. As a result we only allow static variables to contain POD data. This rule completely disallows vector (use C arrays instead), or
string
(use const char []). If you need a static or global variable of a class type, consider initializing a pointer (which will never be freed), from either your main() function or from pthread_once(). Note that this must be a raw pointer, not a "smart" pointer, since the smart pointer's destructor will have the order-of-destructor issue that we are trying to avoid. Classes Classes are the fundamental unit of code in C++. Naturally, we use them extensively. This section lists the main dos and don'ts you should follow when writing a class. Doing Work in Constructors link ▶In general, constructors should merely set member variables to their initial values. Any complex initialization should go in an explicit Init() method. Definition: It is possible to perform initialization in the body of the constructor. Pros: Convenience in typing. No need to worry about whether the class has been initialized or not. Cons: The problems with doing work in constructors are: There is no easy way for constructors to signal errors, short of using exceptions (which are forbidden). If the work fails, we now have an object whose initialization code failed, so it may be an indeterminate state. If the work calls virtual functions, these calls will not get dispatched to the subclass implementations. Future modification to your class can quietly introduce this problem even if your class is not currently subclassed, causing much confusion. If someone creates a global variable of this type (which is against the rules, but still), the constructor code will be called before main(), possibly breaking some implicit assumptions in the constructor code. For instance, gflags will not yet have been initialized. Decision: If your object requires non-trivial initialization, consider having an explicit Init() method. In particular, constructors should not call virtual functions, attempt to raise errors, access potentially uninitialized global variables, etc. Default Constructors link ▶You must define a default constructor if your class defines member variables and has no other constructors. Otherwise the compiler will do it for you, badly. Definition: The default constructor is called when we new a class object with no arguments. It is always called when calling new[] (for arrays). Pros: Initializing structures by default, to hold "impossible" values, makes debugging much easier. Cons: Extra work for you, the code writer. Decision: If your class defines member variables and has no other constructors you must define a default constructor (one that takes no arguments). It should preferably initialize the object in such a way that its internal state is consistent and valid. The reason for this is that if you have no other constructors and do not define a default constructor, the compiler will generate one for you. This compiler generated constructor may not initialize your object sensibly. If your class inherits from an existing class but you add no new member variables, you are not required to have a default constructor. Explicit Constructors link ▶Use the C++ keyword explicit for constructors with one argument. Definition: Normally, if a constructor takes one argument, it can be used as a conversion. For instance, if you define Foo::Foo(
string
name) and then pass a
string
to a function that expects a Foo, the constructor will be called to
convert
the
string
into a Foo and will pass the Foo to your function for you. This can be convenient but is also a source of trouble when things get
convert
ed and new objects created without you meaning them to. Declaring a constructor explicit prevents it from being invoked implicitly as a conversion. Pros: Avoids undesirable conversions. Cons: None. Decision: We require all single argument constructors to be explicit. Always put explicit in front of one-argument constructors in the class definition: explicit Foo(
string
name); The exception is copy constructors, which, in the rare cases when we allow them, should probably not be explicit. Classes that are intended to be transparent wrappers around other classes are also exceptions. Such exceptions should be clearly marked with comments. Copy Constructors link ▶Provide a copy constructor and assignment operator only when necessary. Otherwise, disable them with DISALLOW_COPY_AND_ASSIGN. Definition: The copy constructor and assignment operator are used to create copies of objects. The copy constructor is implicitly invoked by the compiler in some situations, e.g. passing objects by value. Pros: Copy constructors make it easy to copy objects. STL containers require that all contents be copyable and assignable. Copy constructors can be more efficient than CopyFrom()-style workarounds because they combine construction with copying, the compiler can elide them in some contexts, and they make it easier to avoid heap allocation. Cons: Implicit copying of objects in C++ is a rich source of bugs and of performance problems. It also reduces readability, as it becomes hard to track which objects are being passed around by value as opposed to by reference, and therefore where changes to an object are reflected. Decision: Few classes need to be copyable. Most should have neither a copy constructor nor an assignment operator. In many situations, a pointer or reference will work just as well as a copied value, with better performance. For example, you can pass function parameters by reference or pointer instead of by value, and you can store pointers rather than objects in an STL container. If your class needs to be copyable, prefer providing a copy method, such as CopyFrom() or Clone(), rather than a copy constructor, because such methods cannot be invoked implicitly. If a copy method is insufficient in your situation (e.g. for performance reasons, or because your class needs to be stored by value in an STL container), provide both a copy constructor and assignment operator. If your class does not need a copy constructor or assignment operator, you must explicitly disable them. To do so, add dummy declarations for the copy constructor and assignment operator in the private: section of your class, but do not provide any corresponding definition (so that any attempt to use them results in a link error). For convenience, a DISALLOW_COPY_AND_ASSIGN macro can be used: // A macro to disallow the copy constructor and operator= functions // This should be used in the private: declarations for a class #define DISALLOW_COPY_AND_ASSIGN(TypeName) \ TypeName(const TypeName&); \ void operator=(const TypeName&) Then, in class Foo: class Foo { public: Foo(int f); ~Foo(); private: DISALLOW_COPY_AND_ASSIGN(Foo); }; Structs vs. Classes link ▶Use a struct only for passive objects that carry data; everything else is a class. The struct and class keywords behave almost identically in C++. We add our own semantic meanings to each keyword, so you should use the appropriate keyword for the data-type you're defining. structs should be used for passive objects that carry data, and may have associated constants, but lack any functionality other than access/setting the data members. The accessing/setting of fields is done by directly accessing the fields rather than through method invocations. Methods should not provide behavior but should only be used to set up the data members, e.g., constructor, destructor, Initialize(), Reset(), Validate(). If more functionality is required, a class is more appropriate. If in doubt, make it a class. For consistency with STL, you can use struct instead of class for functors and traits. Note that member variables in structs and classes have different naming rules. Inheritance link ▶Composition is often more appropriate than inheritance. When using inheritance, make it public. Definition: When a sub-class inherits from a base class, it includes the definitions of all the data and operations that the parent base class defines. In practice, inheritance is used in two major ways in C++: implementation inheritance, in which actual code is inherited by the child, and interface inheritance, in which only method names are inherited. Pros: Implementation inheritance reduces code size by re-using the base class code as it specializes an existing type. Because inheritance is a compile-time declaration, you and the compiler can understand the operation and detect errors. Interface inheritance can be used to programmatically enforce that a class expose a particular API. Again, the compiler can detect errors, in this case, when a class does not define a necessary method of the API. Cons: For implementation inheritance, because the code implementing a sub-class is spread between the base and the sub-class, it can be more difficult to understand an implementation. The sub-class cannot override functions that are not virtual, so the sub-class cannot change implementation. The base class may also define some data members, so that specifies physical layout of the base class. Decision: All inheritance should be public. If you want to do private inheritance, you should be including an instance of the base class as a member instead. Do not overuse implementation inheritance. Composition is often more appropriate. Try to restrict use of inheritance to the "is-a" case: Bar subclasses Foo if it can reasonably be said that Bar "is a kind of" Foo. Make your destructor virtual if necessary. If your class has virtual methods, its destructor should be virtual. Limit the use of protected to those member functions that might need to be accessed from subclasses. Note that data members should be private. When redefining an inherited virtual function, explicitly declare it virtual in the declaration of the derived class. Rationale: If virtual is omitted, the reader has to check all ancestors of the class in question to determine if the function is virtual or not. Multiple Inheritance link ▶Only very rarely is multiple implementation inheritance actually useful. We allow multiple inheritance only when at most one of the base classes has an implementation; all other base classes must be pure interface classes tagged with the Interface suffix. Definition: Multiple inheritance allows a sub-class to have more than one base class. We distinguish between base classes that are pure interfaces and those that have an implementation. Pros: Multiple implementation inheritance may let you re-use even more code than single inheritance (see Inheritance). Cons: Only very rarely is multiple implementation inheritance actually useful. When multiple implementation inheritance seems like the solution, you can usually find a different, more explicit, and cleaner solution. Decision: Multiple inheritance is allowed only when all superclasses, with the possible exception of the first one, are pure interfaces. In order to ensure that they remain pure interfaces, they must end with the Interface suffix. Note: There is an exception to this rule on Windows. Interfaces link ▶Classes that satisfy certain conditions are allowed, but not required, to end with an Interface suffix. Definition: A class is a pure interface if it meets the following requirements: It has only public pure virtual ("= 0") methods and static methods (but see below for destructor). It may not have non-static data members. It need not have any constructors defined. If a constructor is provided, it must take no arguments and it must be protected. If it is a subclass, it may only be derived from classes that satisfy these conditions and are tagged with the Interface suffix. An interface class can never be directly instantiated because of the pure virtual method(s) it declares. To make sure all implementations of the interface can be destroyed correctly, they must also declare a virtual destructor (in an exception to the first rule, this should not be pure). See Stroustrup, The C++ Programming Language, 3rd edition, section 12.4 for details. Pros: Tagging a class with the Interface suffix lets others know that they must not add implemented methods or non static data members. This is particularly important in the case of multiple inheritance. Additionally, the interface concept is already well-understood by Java programmers. Cons: The Interface suffix lengthens the class name, which can make it harder to read and understand. Also, the interface property may be considered an implementation detail that shouldn't be exposed to clients. Decision: A class may end with Interface only if it meets the above requirements. We do not require the converse, however: classes that meet the above requirements are not required to end with Interface. Operator Overloading link ▶Do not overload operators except in rare, special circumstances. Definition: A class can define that operators such as + and / operate on the class as if it were a built-in type. Pros: Can make code appear more intuitive because a class will behave in the same way as built-in types (such as int). Overloaded operators are more playful names for functions that are less-colorfully named, such as Equals() or Add(). For some template functions to work correctly, you may need to define operators. Cons: While operator overloading can make code more intuitive, it has several drawbacks: It can fool our intuition into thinking that expensive operations are cheap, built-in operations. It is much harder to find the call sites for overloaded operators. Searching for Equals() is much easier than searching for relevant invocations of ==. Some operators work on pointers too, making it easy to introduce bugs. Foo + 4 may do one thing, while &Foo + 4 does something totally different. The compiler does not complain for either of these, making this very hard to debug. Overloading also has surprising ramifications. For instance, if a class overloads unary operator&, it cannot safely be forward-declared. Decision: In general, do not overload operators. The assignment operator (operator=), in particular, is insidious and should be avoided. You can define functions like Equals() and CopyFrom() if you need them. Likewise, avoid the dangerous unary operator& at all costs, if there's any possibility the class might be forward-declared. However, there may be rare cases where you need to overload an operator to interoperate with templates or "standard" C++ classes (such as operator<<(ostream&, const T&) for logging). These are acceptable if fully justified, but you should try to avoid these whenever possible. In particular, do not overload operator== or operator< just so that your class can be used as a key in an STL container; instead, you should create equality and comparison functor types when declaring the container. Some of the STL algorithms do require you to overload operator==, and you may do so in these cases, provided you document why. See also Copy Constructors and Function Overloading. Access Control link ▶Make data members private, and provide access to them through accessor functions as needed (for technical reasons, we allow data members of a test fixture class to be protected when using Google Test). Typically a variable would be called foo_ and the accessor function foo(). You may also want a mutator function set_foo(). Exception: static const data members (typically called kFoo) need not be private. The definitions of accessors are usually inlined in the header file. See also Inheritance and Function Names. Declaration Order link ▶Use the specified order of declarations within a class: public: before private:, methods before data members (variables), etc. Your class definition should start with its public: section, followed by its protected: section and then its private: section. If any of these sections are empty, omit them. Within each section, the declarations generally should be in the following order: Typedefs and Enums Constants (static const data members) Constructors Destructor Methods, including static methods Data Members (except static const data members) Friend declarations should always be in the private section, and the DISALLOW_COPY_AND_ASSIGN macro invocation should be at the end of the private: section. It should be the last thing in the class. See Copy Constructors. Method definitions in the corresponding .cc file should be the same as the declaration order, as much as possible. Do not put large method definitions inline in the class definition. Usually, only trivial or performance-critical, and very short, methods may be defined inline. See Inline Functions for more details. Write Short Functions link ▶Prefer small and focused functions. We recognize that long functions are sometimes appropriate, so no hard limit is placed on functions length. If a function exceeds about 40 lines, think about whether it can be broken up without harming the structure of the program. Even if your long function works perfectly now, someone modifying it in a few months may add new behavior. This could result in bugs that are hard to find. Keeping your functions short and simple makes it easier for other people to read and modify your code. You could find long and complicated functions when working with some code. Do not be intimidated by modifying existing code: if working with such a function proves to be difficult, you find that errors are hard to debug, or you want to use a piece of it in several different contexts, consider breaking up the function into smaller and more manageable pieces. Google-Specific Magic There are various tricks and utilities that we use to make C++ code more robust, and various ways we use C++ that may differ from what you see elsewhere. Smart Pointers link ▶If you actually need pointer semantics, scoped_ptr is great. You should only use std::tr1::shared_ptr under very specific conditions, such as when objects need to be held by STL containers. You should never use auto_ptr. "Smart" pointers are objects that act like pointers but have added semantics. When a scoped_ptr is destroyed, for instance, it deletes the object it's pointing to. shared_ptr is the same way, but implements reference-counting so only the last pointer to an object deletes it. Generally speaking, we prefer that we design code with clear object ownership. The clearest object ownership is obtained by using an object directly as a field or local variable, without using pointers at all. On the other extreme, by their very definition, reference counted pointers are owned by nobody. The problem with this design is that it is easy to create circular references or other strange conditions that cause an object to never be deleted. It is also slow to perform atomic operations every time a value is copied or assigned. Although they are not recommended, reference counted pointers are sometimes the simplest and most elegant way to solve a problem. cpplint link ▶Use cpplint.py to detect style errors. cpplint.py is a tool that reads a source file and identifies many style errors. It is not perfect, and has both false positives and false negatives, but it is still a valuable tool. False positives can be ignored by putting // NOLINT at the end of the line. Some projects have instructions on how to run cpplint.py from their project tools. If the project you are contributing to does not, you can download cpplint.py separately. Other C++ Features Reference Arguments link ▶All parameters passed by reference must be labeled const. Definition: In C, if a function needs to modify a variable, the parameter must use a pointer, eg int foo(int *pval). In C++, the function can alternatively declare a reference parameter: int foo(int &val). Pros: Defining a parameter as reference avoids ugly code like (*pval)++. Necessary for some applications like copy constructors. Makes it clear, unlike with pointers, that NULL is not a possible value. Cons: References can be confusing, as they have value syntax but pointer semantics. Decision: Within function parameter lists all references must be const: void Foo(const
string
&in,
string
*out); In fact it is a very strong convention in Google code that input arguments are values or const references while output arguments are pointers. Input parameters may be const pointers, but we never allow non-const reference parameters. One case when you might want an input parameter to be a const pointer is if you want to emphasize that the argument is not copied, so it must exist for the lifetime of the object; it is usually best to document this in comments as well. STL adapters such as bind2nd and mem_fun do not permit reference parameters, so you must declare functions with pointer parameters in these cases, too. Function Overloading link ▶Use overloaded functions (including constructors) only if a reader looking at a call site can get a good idea of what is happening without having to first figure out exactly which overload is being called. Definition: You may write a function that takes a const
string
& and overload it with another that takes const char*. class MyClass { public: void Analyze(const
string
&text); void Analyze(const char *text, size_t textlen); }; Pros: Overloading can make code more intuitive by allowing an identically-named function to take different arguments. It may be necessary for templatized code, and it can be convenient for Visitors. Cons: If a function is overloaded by the argument types alone, a reader may have to understand C++'s complex matching rules in order to tell what's going on. Also many people are confused by the semantics of inheritance if a derived class overrides only some of the variants of a function. Decision: If you want to overload a function, consider qualifying the name with some information about the arguments, e.g., Append
String
(), AppendInt() rather than just Append(). Default Arguments link ▶We do not allow default function parameters, except in a few uncommon situations explained below. Pros: Often you have a function that uses lots of default values, but occasionally you want to override the defaults. Default parameters allow an easy way to do this without having to define many functions for the rare exceptions. Cons: People often figure out how to use an API by looking at existing code that uses it. Default parameters are more difficult to maintain because copy-and-paste from previous code may not reveal all the parameters. Copy-and-pasting of code segments can cause major problems when the default arguments are not appropriate for the new code. Decision: Except as described below, we require all arguments to be explicitly specified, to force programmers to consider the API and the values they are passing for each argument rather than silently accepting defaults they may not be aware of. One specific exception is when default arguments are used to simulate variable-length argument lists. // Support up to 4 params by using a default empty AlphaNum.
string
StrCat(const AlphaNum &a, const AlphaNum &b = gEmptyAlphaNum, const AlphaNum &c = gEmptyAlphaNum, const AlphaNum &d = gEmptyAlphaNum); Variable-Length Arrays and alloca() link ▶We do not allow variable-length arrays or alloca(). Pros: Variable-length arrays have natural-looking syntax. Both variable-length arrays and alloca() are very efficient. Cons: Variable-length arrays and alloca are not part of Standard C++. More importantly, they allocate a data-dependent amount of stack space that can trigger difficult-to-find memory overwriting bugs: "It ran fine on my machine, but dies mysteriously in production". Decision: Use a safe allocator instead, such as scoped_ptr/scoped_array. Friends link ▶We allow use of friend classes and functions, within reason. Friends should usually be defined in the same file so that the reader does not have to look in another file to find uses of the private members of a class. A common use of friend is to have a FooBuilder class be a friend of Foo so that it can construct the inner state of Foo correctly, without exposing this state to the world. In some cases it may be useful to make a unittest class a friend of the class it tests. Friends extend, but do not break, the encapsulation boundary of a class. In some cases this is better than making a member public when you want to give only one other class access to it. However, most classes should interact with other classes solely through their public members. Exceptions link ▶We do not use C++ exceptions. Pros: Exceptions allow higher levels of an application to decide how to handle "can't happen" failures in deeply nested functions, without the obscuring and error-prone bookkeeping of error codes. Exceptions are used by most other modern languages. Using them in C++ would make it more consistent with Python, Java, and the C++ that others are familiar with. Some third-party C++ libraries use exceptions, and turning them off internally makes it harder to integrate with those libraries. Exceptions are the only way for a constructor to fail. We can simulate this with a factory function or an Init() method, but these require heap allocation or a new "invalid" state, respectively. Exceptions are really handy in testing frameworks. Cons: When you add a throw statement to an existing function, you must examine all of its transitive callers. Either they must make at least the basic exception safety guarantee, or they must never catch the exception and be happy with the program terminating as a result. For instance, if f() calls g() calls h(), and h throws an exception that f catches, g has to be careful or it may not clean up properly. More generally, exceptions make the control flow of programs difficult to evaluate by looking at code: functions may return in places you don't expect. This causes maintainability and debugging difficulties. You can minimize this cost via some rules on how and where exceptions can be used, but at the cost of more that a developer needs to know and understand. Exception safety requires both RAII and different coding practices. Lots of supporting machinery is needed to make writing correct exception-safe code easy. Further, to avoid requiring readers to understand the entire call graph, exception-safe code must isolate logic that writes to persistent state into a "commit" phase. This will have both benefits and costs (perhaps where you're forced to obfuscate code to isolate the commit). Allowing exceptions would force us to always pay those costs even when they're not worth it. Turning on exceptions adds data to each binary produced, increasing compile time (probably slightly) and possibly increasing address space pressure. The availability of exceptions may encourage developers to throw them when they are not appropriate or recover from them when it's not safe to do so. For example, invalid user input should not cause exceptions to be thrown. We would need to make the style guide even longer to document these restrictions! Decision: On their face, the benefits of using exceptions outweigh the costs, especially in new projects. However, for existing code, the introduction of exceptions has implications on all dependent code. If exceptions can be propagated beyond a new project, it also becomes problematic to integrate the new project into existing exception-free code. Because most existing C++ code at Google is not prepared to deal with exceptions, it is comparatively difficult to adopt new code that generates exceptions. Given that Google's existing code is not exception-tolerant, the costs of using exceptions are somewhat greater than the costs in a new project. The conversion process would be slow and error-prone. We don't believe that the available alternatives to exceptions, such as error codes and assertions, introduce a significant burden. Our advice against using exceptions is not predicated on philosophical or moral grounds, but practical ones. Because we'd like to use our open-source projects at Google and it's difficult to do so if those projects use exceptions, we need to advise against exceptions in Google open-source projects as well. Things would probably be different if we had to do it all over again from scratch. There is an exception to this rule (no pun intended) for Windows code. Run-Time Type Information (RTTI) link ▶We do not use Run Time Type Information (RTTI). Definition: RTTI allows a programmer to query the C++ class of an object at run time. Pros: It is useful in some unittests. For example, it is useful in tests of factory classes where the test has to verify that a newly created object has the expected dynamic type. In rare circumstances, it is useful even outside of tests. Cons: A query of type during run-time typically means a design problem. If you need to know the type of an object at runtime, that is often an indication that you should reconsider the design of your class. Decision: Do not use RTTI, except in unittests. If you find yourself in need of writing code that behaves differently based on the class of an object, consider one of the alternatives to querying the type. Virtual methods are the preferred way of executing different code paths depending on a specific subclass type. This puts the work within the object itself. If the work belongs outside the object and instead in some processing code, consider a
double
-dispatch solution, such as the Visitor design pattern. This allows a facility outside the object itself to determine the type of class using the built-in type system. If you think you truly cannot use those ideas, you may use RTTI. But think twice about it. :-) Then think twice again. Do not hand-implement an RTTI-like workaround. The arguments against RTTI apply just as much to workarounds like class hierarchies with type tags. Casting link ▶Use C++ casts like static_cast(). Do not use other cast formats like int y = (int)x; or int y = int(x);. Definition: C++ introduced a different cast system from C that distinguishes the types of cast operations. Pros: The problem with C casts is the ambiguity of the operation; sometimes you are doing a conversion (e.g., (int)3.5) and sometimes you are doing a cast (e.g., (int)"hello"); C++ casts avoid this. Additionally C++ casts are more visible when searching for them. Cons: The syntax is nasty. Decision: Do not use C-style casts. Instead, use these C++-style casts. Use static_cast as the equivalent of a C-style cast that does value conversion, or when you need to explicitly up-cast a pointer from a class to its superclass. Use const_cast to remove the const qualifier (see const). Use reinterpret_cast to do unsafe conversions of pointer types to and from integer and other pointer types. Use this only if you know what you are doing and you understand the aliasing issues. Do not use dynamic_cast except in test code. If you need to know type information at runtime in this way outside of a unittest, you probably have a design flaw. Streams link ▶Use streams only for logging. Definition: Streams are a replacement for printf() and scanf(). Pros: With streams, you do not need to know the type of the object you are printing. You do not have problems with format
string
s not matching the argument list. (Though with gcc, you do not have that problem with printf either.) Streams have automatic constructors and destructors that open and close the relevant files. Cons: Streams make it difficult to do functionality like pread(). Some formatting (particularly the common format
string
idiom %.*s) is difficult if not impossible to do efficiently using streams without using printf-like hacks. Streams do not support operator reordering (the %1s directive), which is helpful for internationalization. Decision: Do not use streams, except where required by a logging interface. Use printf-like routines instead. There are various pros and cons to using streams, but in this case, as in many other cases, consistency trumps the debate. Do not use streams in your code. Extended Discussion There has been debate on this issue, so this explains the reasoning in greater depth. Recall the Only One Way guiding principle: we want to make sure that whenever we do a certain type of I/O, the code looks the same in all those places. Because of this, we do not want to allow users to decide between using streams or using printf plus Read/Write/etc. Instead, we should settle on one or the other. We made an exception for logging because it is a pretty specialized application, and for historical reasons. Proponents of streams have argued that streams are the obvious choice of the two, but the issue is not actually so clear. For every advantage of streams they point out, there is an equivalent disadvantage. The biggest advantage is that you do not need to know the type of the object to be printing. This is a fair point. But, there is a downside: you can easily use the wrong type, and the compiler will not warn you. It is easy to make this kind of mistake without knowing when using streams. cout << this; // Prints the address cout << *this; // Prints the contents The compiler does not generate an error because << has been overloaded. We discourage overloading for just this reason. Some say printf formatting is ugly and hard to read, but streams are often no better. Consider the following two fragments, both with the same typo. Which is easier to discover? cerr << "Error connecting to '"
hostname.first << ":"
hostname.second << ": "
hostname.first, foo->bar()->hostname.second, strerror(errno)); And so on and so forth for any issue you might bring up. (You could argue, "Things would be better with the right wrappers," but if it is true for one scheme, is it not also true for the other? Also, remember the goal is to make the language smaller, not add yet more machinery that someone has to learn.) Either path would yield different advantages and disadvantages, and there is not a clearly superior solution. The simplicity doctrine mandates we settle on one of them though, and the majority decision was on printf + read/write. Preincrement and Predecrement link ▶Use prefix form (++i) of the increment and decrement operators with iterators and other template objects. Definition: When a variable is incremented (++i or i++) or decremented (--i or i--) and the value of the expression is not used, one must decide whether to preincrement (decrement) or postincrement (decrement). Pros: When the return value is ignored, the "pre" form (++i) is never less efficient than the "post" form (i++), and is often more efficient. This is because post-increment (or decrement) requires a copy of i to be made, which is the value of the expression. If i is an iterator or other non-scalar type, copying i could be expensive. Since the two types of increment behave the same when the value is ignored, why not just always pre-increment? Cons: The tradition developed, in C, of using post-increment when the expression value is not used, especially in for loops. Some find post-increment easier to read, since the "subject" (i) precedes the "verb" (++), just like in English. Decision: For simple scalar (non-object) values there is no reason to prefer one form and we allow either. For iterators and other template types, use pre-increment. Use of const link ▶We strongly recommend that you use const whenever it makes sense to do so. Definition: Declared variables and parameters can be preceded by the keyword const to indicate the variables are not changed (e.g., const int foo). Class functions can have the const qualifier to indicate the function does not change the state of the class member variables (e.g., class Foo { int Bar(char c) const; };). Pros: Easier for people to understand how variables are being used. Allows the compiler to do better type checking, and, conceivably, generate better code. Helps people convince themselves of program correctness because they know the functions they call are limited in how they can modify your variables. Helps people know what functions are safe to use without locks in multi-threaded programs. Cons: const is viral: if you pass a const variable to a function, that function must have const in its prototype (or the variable will need a const_cast). This can be a particular problem when calling library functions. Decision: const variables, data members, methods and arguments add a level of compile-time type checking; it is better to detect errors as soon as possible. Therefore we strongly recommend that you use const whenever it makes sense to do so: If a function does not modify an argument passed by reference or by pointer, that argument should be const. Declare methods to be const whenever possible. Accessors should almost always be const. Other methods should be const if they do not modify any data members, do not call any non-const methods, and do not return a non-const pointer or non-const reference to a data member. Consider making data members const whenever they do not need to be modified after construction. However, do not go crazy with const. Something like const int * const * const x; is likely overkill, even if it accurately describes how const x is. Focus on what's really useful to know: in this case, const int** x is probably sufficient. The mutable keyword is allowed but is unsafe when used with threads, so thread safety should be carefully considered first. Where to put the const Some people favor the form int const *foo to const int* foo. They argue that this is more readable because it's more consistent: it keeps the rule that const always follows the object it's describing. However, this consistency argument doesn't apply in this case, because the "don't go crazy" dictum eliminates most of the uses you'd have to be consistent with. Putting the const first is arguably more readable, since it follows English in putting the "adjective" (const) before the "noun" (int). That said, while we encourage putting const first, we do not require it. But be consistent with the code around you! Integer Types link ▶Of the built-in C++ integer types, the only one used is int. If a program needs a variable of a different size, use a precise-width integer type from , such as int16_t. Definition: C++ does not specify the sizes of its integer types. Typically people assume that short is 16 bits, int is 32 bits, long is 32 bits and long long is 64 bits. Pros: Uniformity of declaration. Cons: The sizes of integral types in C++ can vary based on compiler and architecture. Decision: defines types like int16_t, uint32_t, int64_t, etc. You should always use those in preference to short, unsigned long long and the like, when you need a guarantee on the size of an integer. Of the C integer types, only int should be used. When appropriate, you are welcome to use standard types like size_t and ptrdiff_t. We use int very often, for integers we know are not going to be too big, e.g., loop counters. Use plain old int for such things. You should assume that an int is at least 32 bits, but don't assume that it has more than 32 bits. If you need a 64-bit integer type, use int64_t or uint64_t. For integers we know can be "big", use int64_t. You should not use the unsigned integer types such as uint32_t, unless the quantity you are representing is really a bit pattern rather than a number, or unless you need defined twos-complement overflow. In particular, do not use unsigned types to say a number will never be negative. Instead, use assertions for this. On Unsigned Integers Some people, including some textbook authors, recommend using unsigned types to represent numbers that are never negative. This is intended as a form of self-documentation. However, in C, the advantages of such documentation are outweighed by the real bugs it can introduce. Consider: for (unsigned int i = foo.Length()-1; i >= 0; --i) ... This code will never terminate! Sometimes gcc will notice this bug and warn you, but often it will not. Equally bad bugs can occur when comparing signed and unsigned variables. Basically, C's type-promotion scheme causes unsigned types to behave differently than one might expect. So, document that a variable is non-negative using assertions. Don't use an unsigned type. 64-bit Portability link ▶Code should be 64-bit and 32-bit friendly. Bear in mind problems of printing, comparisons, and structure alignment. printf() specifiers for some types are not cleanly portable between 32-bit and 64-bit systems. C99 defines some portable format specifiers. Unfortunately, MSVC 7.1 does not understand some of these specifiers and the standard is missing a few, so we have to define our own ugly versions in some cases (in the style of the standard include file inttypes.h): // printf macros for size_t, in the style of inttypes.h #ifdef _LP64 #define __PRIS_PREFIX "z" #else #define __PRIS_PREFIX #endif // Use these macros after a % in a printf format
string
// to get correct 32/64 bit behavior, like this: // size_t size = records.size(); // printf("%"PRIuS"\n", size); #define PRIdS __PRIS_PREFIX "d" #define PRIxS __PRIS_PREFIX "x" #define PRIuS __PRIS_PREFIX "u" #define PRIXS __PRIS_PREFIX "X" #define PRIoS __PRIS_PREFIX "o" Type DO NOT use DO use Notes void * (or any pointer) %lx %p int64_t %qd, %lld %"PRId64" uint64_t %qu, %llu, %llx %"PRIu64", %"PRIx64" size_t %u %"PRIuS", %"PRIxS" C99 specifies %zu ptrdiff_t %d %"PRIdS" C99 specifies %zd Note that the PRI* macros expand to independent
string
s which are concatenated by the compiler. Hence if you are using a non-constant format
string
, you need to insert the value of the macro into the format, rather than the name. It is still possible, as usual, to include length specifiers, etc., after the % when using the PRI* macros. So, e.g. printf("x = %30"PRIuS"\n", x) would expand on 32-bit Linux to printf("x = %30" "u" "\n", x), which the compiler will treat as printf("x = %30u\n", x). Remember that sizeof(void *) != sizeof(int). Use intptr_t if you want a pointer-sized integer. You may need to be careful with structure alignments, particularly for structures being stored on disk. Any class/structure with a int64_t/uint64_t member will by default end up being 8-byte aligned on a 64-bit system. If you have such structures being shared on disk between 32-bit and 64-bit code, you will need to ensure that they are packed the same on both architectures. Most compilers offer a way to alter structure alignment. For gcc, you can use __attribute__((packed)). MSVC offers #pragma pack() and __declspec(align()). Use the LL or ULL suffixes a
au3反编译源码
au3反编译源码 myAut2Exe - The Open Source AutoIT Script Decompiler 2.9 ======================================================== *New* full support for AutoIT v3.2.6++ :) ... mmh here's what I merely missed in the 'public sources 3.1.0' This program is for studying the 'Compiled' AutoIt3 format. AutoHotKey was developed from AutoIT and so scripts are nearly the same. Drag the compiled *.exe or *.a3x into the AutoIT Script Decompiler textbox. To copy text or to enlarge the log window
double
click on it. Supported Obfuscators: 'Jos van der Zande AutoIt3 Source Obfuscator v1.0.14 [June 16, 2007]' , 'Jos van der Zande AutoIt3 Source Obfuscator v1.0.15 [July 1, 2007]' , 'Jos van der Zande AutoIt3 Source Obfuscator v1.0.20 [Sept 8, 2007]' , 'Jos van der Zande AutoIt3 Source Obfuscator v1.0.22 [Oct 18, 2007]' , 'Jos van der Zande AutoIt3 Source Obfuscator v1.0.24 [Feb 15, 2008]' , 'EncodeIt 2.0' and 'Chr()
string
encode' Tested with: AutoIT : v3. 3. 0.0 and AutoIT : v2.64. 0.0 and AutoHotKey: v1.0.48.5 The options: =========== 'Force Old Script Type' Grey means auto detect and is the best in most cases. However if auto detection fails or is fooled through modification try to enable/disable this setting 'Don't delete temp files (compressed script)' this will keep *.pak files you may try to unpack manually with'LZSS.exe' as well as *.tok DeTokeniser files, tidy backups and *.tbl (<-Used in van Zande obfucation). If enable it will keep AHK-Scripts as they are and doesn't remove the linebreaks at the beginning Default:OFF 'Verbose LogOutput' When checked you get verbose information when decompiling(DeTokenise) new 3.2.6+ compiled Exe Default:OFF 'Restore Includes' will separated/restore includes. requires ';
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