#pragma hdrstop等语句的意思?

zleia 2003-10-16 10:19:56
在bcb中有许多的预编译指令象:#pragma hdrstop,#pragma package(smart_init)......等的意思.哪位大侠能给我讲一下bcb中的这些指令的具体含义和用法?



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cupidvenus 2003-10-17
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那么多,还是查帮助吧。
TopCoderONE 2003-10-17
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查帮助,说明很详细的。
我不懂电脑 2003-10-17
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Syntax

#pragma hdrstop

Description

This directive terminates the list of header files eligible for precompilation. You can use it to reduce the amount of disk space used by
precompiled headers.

Precompiled header files can be shared between the source files of your project only if the #include directives before #pragma hdrstop are identical. Therefore, you get the best compiler performance if you include common header files of your project before the
#pragma hdrstop, and specific ones after it. Make sure the #include directives before the #pragma hdrstop are identical in all the source files, or that there are only very few variations.

The integrated development environment generates code to enhance precompiled header performance. For example, after a New Application, source file "Unit1.cpp" will look like this (comments added):

#include <vcl.h> // common header file

#pragma hdrstop // terminate list here

#include "Unit1.h" // specific header file
// ....

Use this pragma directive only in source files. The pragma has no effect when it is used in a header file.
Kabin 2003-10-17
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#pragma hdrstop表示预编译头文件到此为止,后面的头文件不进行预编译。BCB可以预编译头文件以加快链接的速度,但如果所有头文件都进行预编译又可能占太多磁盘空间,所以使用这个选项排除一些头文件。

有时单元之间有依赖关系,比如单元A依赖单元B,所以单元B要先于单元A编译。你可以用#pragma startup指定编译优先级,如果使用了#pragma package(smart_init) ,BCB就会根据优先级的大小先后编译。

#pragma resource "*.dfm"表示把*.dfm文件中的资源加入工程。*.dfm中包括窗体外观的定义。
tigerhohoo 2003-10-17
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Syntax

#pragma hdrstop

Description

This directive terminates the list of header files eligible for precompilation. You can use it to reduce the amount of disk space used by precompiled headers.

Precompiled header files can be shared between the source files of your project only if the #include directives before #pragma hdrstop are identical. Therefore, you get the best compiler performance if you include common header files of your project before the #pragma hdrstop, and specific ones after it. Make sure the #include directives before the #pragma hdrstop are identical in all the source files, or that there are only very few variations.

The integrated development environment generates code to enhance precompiled header performance. For example, after a New Application, source file "Unit1.cpp" will look like this (comments added):
请多参考联机帮助。
#include <vcl.h> // common header file

#pragma hdrstop // terminate list here

#include "Unit1.h" // specific header file
// ....

Use this pragma directive only in source files. The pragma has no effect when it is used in a header file.
ljianq 2003-10-17
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我这有篇关于预编译的文章,是前些天论台上一位网友提供的,地址忘了。

需要的话,可以发给楼主。
ljianq 2003-10-17
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#pragma hdrstop指令告诉编译程序停止产生预先编译的映象。任何在hdrstop指令前
的#include文件都将预编译,而在该指令后的#include文件都将不会预编译。
附录:源程序 //-------------------主窗体 查询与浏览--------------------------------------- #include #pragma hdrstop #include "Unit1.h" #include "Unit2.h" #include "Unit3.h" #include "Unit4.h" #include "Unit5.h" #include "Unit6.h" #pragma package(smart_init) #pragma resource "*.dfm" TFmain *Fmain; bool onshow=false; __fastcall TFmain::TFmain(TComponent* Owner) : TForm(Owner) { } void __fastcall TFmain::N5Click(TObject *Sender) { Close();//退出程序 } void __fastcall TFmain::SpeedButton3Click(TObject *Sender) { DataModule3->ADOQuery1->First() ; StatusBar1->Panels->Items[0]->Text="数据指向第一个"; } void __fastcall TFmain::SpeedButton1Click(TObject *Sender) { DataModule3->ADOQuery1->Prior() ; StatusBar1->Panels->Items[0]->Text="数据指向上一个"; } void __fastcall TFmain::SpeedButton2Click(TObject *Sender) { DataModule3->ADOQuery1->Next() ; StatusBar1->Panels->Items[0]->Text="数据指向下一个"; } void __fastcall TFmain::SpeedButton4Click(TObject *Sender) { DataModule3->ADOQuery1->Last() ; StatusBar1->Panels->Items[0]->Text="数据指向最后"; } void __fastcall TFmain::Button2Click(TObject *Sender) { //添加新的数据 Fadd->Caption="添加数据"; DataModule3->ADOQuery1->Append() ; Fadd->ShowModal() ; } void __fastcall TFmain::FormClose(TObject *Sender, TCloseAction &Action) { //对退出程序做确认处理 if(MessageBox(this->Handle,"确定要退出吗?","提示",MB_YESNO+MB_ICONQUESTION) == IDNO) Action=caNone; } void __fastcall TFmain::N10Click(TObject *Sender) { AboutBox->ShowModal() ; //显示关于对话框 } void __fastcall TFmain::Button4Click(TObject *Sender) { //以下为查找语句 AnsiString sql; if(Edit1->Text=="")return; if( ComboBox1->Text =="精确")sql=" ='"+Edit1->Text+"';"; else sql=" like '%"+Edit1->Text+"%';"; sql="select * from renshi where "+ComboBox2->Text+sql; StatusBar1->Panels->Items[0]->Text=sql; DataModule3->ADOQuery1->Active =false; DataModule3->ADOQuery1->SQL->Clear(); DataModule3->ADOQuery1->SQL->Add(sql); DataModule3->ADOQuery1->Active =true; if(DataModule3->ADOQuery1->RecordCount==0) StatusBar1->Panels->Items[1]->Text="无符合条件数据"; else StatusBar1->Panels->Items[1]->Text="符合条件数据个数为:"+IntToStr(DataModule3->ADOQuery1->RecordCount); } void __fastcall TFmain::Button6Click(TObject *Sender) { //以下为显示所有数据 AnsiString sql; sql="select * from renshi;"; StatusBar1->Panels->Items[0]->Text="显示全部数据"; DataModule3->ADOQuery1->Active =false; DataModule3->ADOQuery1->SQL->Clear(); DataModule3->ADOQuery1->SQL->Add(sql); DataModule3->ADOQuery1->Active =true; if(DataModule3->ADOQuery1->RecordCount==0) StatusBar1->Panels->Items[1]->Text="无符合条件数据"; else StatusBar1->Panels->Items[1]->Text="数据总量为:"+IntToStr(DataModule3->ADOQuery1->RecordCount); } void __fastcall TFmain::Button1Click(TObject *Sender) { //刷新显示 DataModule3->ADOQuery1->Active =false; DataModule3->ADOQuery1->Active =true; } void __fastcall TFmain::N9Click(TObject *Sender) { //帮助内容 ShowMessage("\ 大家好,虽然只是一个简单的程序但是也要写帮助。\n\ 简单的操作如下:\n\ 一、打开程序。\n\ 二、可以进行数据的添加、删除、浏览、查找\n\ 三、关闭。\n\ 谢谢使用!\n\ "); } void __fastcall TFmain::Button3Click(TObject *Sender) { //数据删除操作 AnsiString printstr="确定删除编号为"+DataModule3->ADOQuery1->FieldByName("编号")->AsString+"的数据吗?"; if(MessageDlg(printstr,mtWarning,TMsgDlgButtons() << mbOK Delete() ; StatusBar1->Panels->Items[0]->Text="数据已经删除"; } } void __fastcall TFmain::N3Click(TObject *Sender) { //更改显示字体 if(FontDialog1->Execute())Fmain->Font=FontDialog1->Font; } void __fastcall TFmain::N12Click(TObject *Sender) { //更改窗体颜色 if(ColorDialog1->Execute()) { Fmain->Color=ColorDialog1->Color;//主窗体 Fadd->Color=ColorDialog1->Color; //添加、修改窗体 } } void __fastcall TFmain::N13Click(TObject *Sender) { //更改数据域颜色 if(ColorDialog1->Execute()) DBGrid1->Color=ColorDialog1->Color; } void __fastcall TFmain::N11Click(TObject *Sender) { Fshow->QuickRep1->Preview();//打印数据 } void __fastcall TFmain::Button5Click(TObject *Sender) { Fadd->Caption="修改数据"; Fadd->ShowModal() ; //修改数据 } void __fastcall TFmain::FormShow(TObject *Sender) { if(onshow==false) { Fwelcome->ShowModal() ; onshow=true; return; } } //-------------------------------------------------------------------------- //------------系统封面------------------------------------------------------ #include #pragma hdrstop #include "Unit2.h" #include "Unit1.h" #pragma package(smart_init) #pragma resource "*.dfm" TFwelcome *Fwelcome; int logintime=15; //进入系统等待时间X秒 __fastcall TFwelcome::TFwelcome(TComponent* Owner) : TForm(Owner) { } void __fastcall TFwelcome::Timer1Timer(TObject *Sender) { if(logintime==0){ Timer1->Enabled=false; Close(); } logintime--; SpeedButton1->Caption ="进入("+IntToStr(logintime)+")"; } void __fastcall TFwelcome::SpeedButton2Click(TObject *Sender) { Application->Terminate() ; } void __fastcall TFwelcome::SpeedButton1Click(TObject *Sender) { logintime=15; Timer1->Enabled=false; Close(); } //-------------------------------------------------------------------------- //---------------------数据修改窗体----------------------------------------- #include #pragma hdrstop #include "Unit4.h" #include "Unit3.h" #pragma package(smart_init) #pragma resource "*.dfm" TFadd *Fadd; __fastcall TFadd::TFadd(TComponent* Owner) : TForm(Owner) { } void __fastcall TFadd::Button1Click(TObject *Sender) { if(DBEdit1->Text =="")return; DataModule3->ADOQuery1->Refresh() ; Close(); } void __fastcall TFadd::Button2Click(TObject *Sender) { DataModule3->ADOQuery1->Cancel() ; Close(); } void __fastcall TFadd::FormClose(TObject *Sender, TCloseAction &Action) { DataModule3->ADOQuery1->Cancel() ; } //--------------------------------------------------------------------------

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