如果出现这种错误：“uafxcwd.lib(dllmodul.obj) : error LNK2005: _DllMain@12 already defined in main.obj ”或者“mfcs42ud.lib(dllmodul.obj) : error LNK2005: _DllMain@12 already defined in main.obj ”，那么“See if you have _AFXDLL and _USRDLL in the preprocessor definitions. Try removing one of them”。具体位置：IDE中 菜单Project / Setting / C/C++ / preprocessor definition 。
Project / Setting / C/C++ / 代码生成---->>运行时库---->>多线程调试 DLL (/MDd)
资深员工说加入以下代码：
#include "stdafx.h"
#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
#define new DEBUG_NEW
/
// global data
// The following symbol used to force inclusion of this module for _USRDLL
#ifdef _X86_
extern "C" { int _afxForceUSRDLL; }
#else
extern "C" { int __afxForceUSRDLL; }
#endif
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