問題場景：
我的工程裏面引入了libpng.lib、libzlib.lib 兩個現成的靜態庫以及一個zlib1.dll文件，編譯就出現了問題：
先把Character Set設置爲:Not Set
(Configuration Properties -> Genearl -> Project Defaults -> Character Set)
如果沒有調用TRACE函數，在編譯的過程中出現了警告：
LINK : warning LNK4098: defaultlib 'LIBCMT' conflicts with use of other libs; use /NODEFAULTLIB:library
如果調用了TRACE函數，進行編譯輸出如下錯誤：
1>ManifestResourceCompile:
1> All outputs are up-to-date.
1>LIBCMT.lib(invarg.obj) : error LNK2005: __invoke_watson already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(mbctype.obj) : error LNK2005: __setmbcp already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(setlocal.obj) : error LNK2005: __configthreadlocale already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(invarg.obj) : error LNK2005: __invoke_watson already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(setlocal.obj) : error LNK2005: __configthreadlocale already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(mlock.obj) : error LNK2005: __unlock already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(mlock.obj) : error LNK2005: __lock already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(winxfltr.obj) : error LNK2005: __XcptFilter already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(crt0dat.obj) : error LNK2005: __initterm_e already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(crt0dat.obj) : error LNK2005: _exit already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(crt0dat.obj) : error LNK2005: __exit already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(crt0dat.obj) : error LNK2005: __cexit already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(crt0dat.obj) : error LNK2005: __amsg_exit already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(_file.obj) : error LNK2005: ___iob_func already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(hooks.obj) : error LNK2005: "void __cdecl terminate(void)" (?terminate@@YAXXZ) already defined in msvcrtd.lib(MSVCR100D.dll)
1>LIBCMT.lib(crt0init.obj) : error LNK2005: ___xi_a already defined in msvcrtd.lib(cinitexe.obj)
1>LIBCMT.lib(crt0init.obj) : error LNK2005: ___xi_z already defined in msvcrtd.lib(cinitexe.obj)
1>LIBCMT.lib(crt0init.obj) : error LNK2005: ___xc_a already defined in msvcrtd.lib(cinitexe.obj)
1>LIBCMT.lib(crt0init.obj) : error LNK2005: ___xc_z already defined in msvcrtd.lib(cinitexe.obj)
1>LIBCMT.lib(errmode.obj) : error LNK2005: ___set_app_type already defined in msvcrtd.lib(MSVCR100D.dll)
1>msvcrtd.lib(MSVCR100D.dll) : error LNK2005: __setmbcp already defined in LIBCMT.lib(mbctype.obj)
1>LINK : warning LNK4098: defaultlib 'msvcrtd.lib' conflicts with use of other libs; use /NODEFAULTLIB:library
1>LINK : warning LNK4098: defaultlib 'LIBCMT' conflicts with use of other libs; use /NODEFAULTLIB:library
1>LIBCMT.lib(crt0.obj) : error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup
1>E:\dev\proj\cpp\mfc\PngTest\Debug\PngTest.exe : fatal error LNK1120: 1 unresolved externals
1>
1>Build FAILED.
1>
1>Time Elapsed 00:00:00.92
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========解決辦法：
Configuration Properties -> Linker -> Input -> Ignore Specific Defualt Libraries : LIBCMT.lib
網上的解決辦法：
在自己代碼連接其他lib或者dll時，msvcrt.lib和libcmt.lib衝突，只需要把使用./MD(多線程dll)重新編譯下
lib或者dll文件，就可以了。