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LIBCD.lib(crt0.obj) : error LNK2001: unresolved external symbol _main 怎么回事?

icegoblin 2001-07-22 10:08:45
出了个这样的错,那位能告之吗?
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111222 2001-08-11
回复人:UltraUnAsm() (2000-7-21 16:31:00) 得40分
我猜你是直接打开(或编辑)了一个Winmain程序就Build。VC++此时假定你要建立Console程序而不是GUI程序,而Console程序的Startup Code要载入的是main()而不是Winmain(),导致连接失败。改正的方法是将菜单Project/Settings下Link项Option内的/subsystem:console改为/subsystem:windows。更稳妥的做法是以后先New一个Win32 GUI Project,再拷贝入你的程序,再Build。
 回复人:javaonline(javaonline) (2001-3-7 17:56:00) 得0分
我刚好也碰到了这个问题,我查了一下 MSDN
出现这个错误的原因是你在你的程序中使用了 CRT 函数所致,而且,这个错误只出现在Release 中,解决的方法有两种:
一:找出你所的 CRT 函数,改用非 CRT 函数
二:去掉预编译 _ATL_MIN_CRT 就可以了,但是这样以来就会增加编译后文件的大小,大概几十 K 的样子。

原文如下:

INFO: LNK2001 Error ATL Release Build
ID: Q165076



--------------------------------------------------------------------------------
The information in this article applies to:

Microsoft Active Template Library, versions 2.0, 2.1, 3.0

--------------------------------------------------------------------------------


SUMMARY
Microsoft Active Template Library COM AppWizard generates a release build of your project using macro _ATL_MIN_CRT. Selecting this configuration causes the C run-time (CRT) library startup code to not be linked into your project. If you use functions or code in your project that require the use of the C run-time library startup code, you may experience LNK2001 - unresolved external errors when you try to build the release version of your project.



MORE INFORMATION
You can use some C run-time functions without requiring the CRT startup code. Examples include the mem* functions. Other functions require the CRT startup code. CRT string comparisons for example require the startup code as the CRT initializes some tables used for comparing. Global objects that have constructors also require the startup code. In Visual C++ 5.0, statically linking the startup code adds about 25K to your image (in Visual C++ 4.2 it is about 20K).

Following are some suggestions for finding the cause of the LNK2001 errors:

In the linker options there is an "ignore libraries" edit box. Enter Libcmt.lib into it, and build. You get several unresolved externals. This list is everything that you are using from the CRT. Look for things that you think may be pulling in the startup code and remove them if you can.


Don't ignore Libcmt.lib, but turn on the verbose flag for the linker. From this, you can see what is triggering CRT startup code to get pulled in.


If you decide that you really need the startup code, then remove the _ATL_MIN_CRT define from the project settings. You can also dynamically link to the CRT, which reduces your image size but requires the CRT's DLL. If you turn on exception handling you have to pull in the startup code. Even when building minsize the default is to statically link to the CRT and use _ATL_MIN_CRT.
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icegoblin 2001-07-22
Using incorrect /SUBSYSTEM or /ENTRY settings can cause LNK2001. For example, if you write a character-based application (a console application) and specify /SUBSYSTEM:WINDOWS, you will get an unresolved external for WinMain.
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icegoblin 2001-07-22
终于改好了。
其实将project setting的link卡中的opject option中的 /subsystem:console删去就行了。
呵呵,从MSDN上看来的,还没仔细研究,就知道这样改就行了。 分数加给我自己了 :)
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icegoblin 2001-07-22
我改了,还是不行啊??
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masterz 2001-07-22
把project setting中的preprocessor _CONSOLE改为 _WINDOWS
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icegoblin 2001-07-22
我并没有用main啊?
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