编译一个含数据库操作的工程时出现如下错误，
Linking...
LIBC.lib(crt0dat.obj) : error LNK2005: _exit already defined in msvcrtd.lib(MSVCRTD.dll)
LIBC.lib(crt0dat.obj) : error LNK2005: __exit already defined in msvcrtd.lib(MSVCRTD.dll)
LIBC.lib(winxfltr.obj) : error LNK2005: __XcptFilter already defined in msvcrtd.lib(MSVCRTD.dll)
LIBC.lib(crt0init.obj) : error LNK2005: ___xc_z already defined in msvcrtd.lib(cinitexe.obj)
LIBC.lib(crt0init.obj) : error LNK2005: ___xc_a already defined in msvcrtd.lib(cinitexe.obj)
LIBC.lib(crt0init.obj) : error LNK2005: ___xi_z already defined in msvcrtd.lib(cinitexe.obj)
LIBC.lib(crt0init.obj) : error LNK2005: ___xi_a already defined in msvcrtd.lib(cinitexe.obj)
msvcrtd.lib(MSVCRTD.dll) : error LNK2005: __setmbcp already defined in LIBC.lib(mbctype.obj)
LINK : warning LNK4098: defaultlib "msvcrtd.lib" conflicts with use of other libs; use /NODEFAULTLIB:library
LINK : warning LNK4098: defaultlib "LIBC" conflicts with use of other libs; use /NODEFAULTLIB:library
LIBC.lib(crt0.obj) : error LNK2001: unresolved external symbol _main
Debug/CardCenter.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.
解决方法：Project->settings->link->category->input->ignore libraries: 输入LIBC.lib OK