原来是项目属性里的运行库设置的原因

Linking...
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: __thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@ABV01@@Z) already defined in GameManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: __thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::~basic_string<char,struct std::char_traits<char>,class std::allocator<char> >(void)" (??1?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@XZ) already defined in Main.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: __thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >(void)" (??0?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@XZ) already defined in InputManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "bool __cdecl std::operator<<char,struct std::char_traits<char>,class std::allocator<char> >(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??$?MDU?$char_traits@D@std@@V?$allocator@D@1@@std@@YA_NABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@0@Z) already defined in InputManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: __thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >(char const *)" (??0?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@PBD@Z) already defined in GameManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > & __thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::operator=(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??4?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAEAAV01@ABV01@@Z) already defined in SoundManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > & __thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::operator=(char const *)" (??4?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAEAAV01@PBD@Z) already defined in class.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: void __thiscall std::_Mutex::_Lock(void)" (?_Lock@_Mutex@std@@QAEXXZ) already defined in libcpmt.lib(xmutex.obj)
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: void __thiscall std::_Mutex::_Unlock(void)" (?_Unlock@_Mutex@std@@QAEXXZ) already defined in libcpmt.lib(xmutex.obj)
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: class std::basic_ostream<char,struct std::char_traits<char> > & __thiscall std::basic_ostream<char,struct std::char_traits<char> >::flush(void)" (?flush@?$basic_ostream@DU?$char_traits@D@std@@@std@@QAEAAV12@XZ) already defined in InputManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: void __thiscall std::basic_ostream<char,struct std::char_traits<char> >::_Osfx(void)" (?_Osfx@?$basic_ostream@DU?$char_traits@D@std@@@std@@QAEXXZ) already defined in InputManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "bool __cdecl std::uncaught_exception(void)" (?uncaught_exception@std@@YA_NXZ) already defined in libcpmt.lib(uncaught.obj)
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: void __thiscall std::basic_ios<char,struct std::char_traits<char> >::setstate(int,bool)" (?setstate@?$basic_ios@DU?$char_traits@D@std@@@std@@QAEXH_N@Z) already defined in InputManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: int __thiscall std::basic_streambuf<char,struct std::char_traits<char> >::sputc(char)" (?sputc@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEHD@Z) already defined in InputManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: void __thiscall std::basic_ostringstream<char,struct std::char_traits<char>,class std::allocator<char> >::`vbase destructor'(void)" (??_D?$basic_ostringstream@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAEXXZ) already defined in InputManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall std::basic_ostringstream<char,struct std::char_traits<char>,class std::allocator<char> >::str(void)const " (?str@?$basic_ostringstream@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QBE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@2@XZ) already defined in InputManager.obj
msvcprt.lib(MSVCP80.dll) : error LNK2005: "public: __thiscall std::basic_ostringstream<char,struct std::char_traits<char>,class std::allocator<char> >::basic_ostringstream<char,struct std::char_traits<char>,class std::allocator<char> >(int)" (??0?$basic_ostringstream@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@H@Z) already defined in InputManager.obj
MSVCRT.lib(MSVCR80.dll) : error LNK2005: "public: __thiscall std::exception::exception(char const * const &)" (??0exception@std@@QAE@ABQBD@Z) already defined in LIBCMT.lib(stdexcpt.obj)
MSVCRT.lib(MSVCR80.dll) : error LNK2005: "public: virtual __thiscall std::exception::~exception(void)" (??1exception@std@@UAE@XZ) already defined in LIBCMT.lib(stdexcpt.obj)
MSVCRT.lib(MSVCR80.dll) : error LNK2005: "public: __thiscall std::exception::exception(void)" (??0exception@std@@QAE@XZ) already defined in LIBCMT.lib(stdexcpt.obj)
MSVCRT.lib(MSVCR80.dll) : error LNK2005: __invalid_parameter_noinfo already defined in LIBCMT.lib(invarg.obj)
MSVCRT.lib(MSVCR80.dll) : error LNK2005: "public: __thiscall std::exception::exception(class std::exception const &)" (??0exception@std@@QAE@ABV01@@Z) already defined in LIBCMT.lib(stdexcpt.obj)
MSVCRT.lib(MSVCR80.dll) : error LNK2005: _strtoul already defined in LIBCMT.lib(strtol.obj)
MSVCRT.lib(ti_inst.obj) : error LNK2005: "private: __thiscall type_info::type_info(class type_info const &)" (??0type_info@@AAE@ABV0@@Z) already defined in LIBCMT.lib(typinfo.obj)
MSVCRT.lib(ti_inst.obj) : error LNK2005: "private: class type_info & __thiscall type_info::operator=(class type_info const &)" (??4type_info@@AAEAAV0@ABV0@@Z) already defined in LIBCMT.lib(typinfo.obj)
LINK : warning LNK4098: defaultlib 'MSVCRT' conflicts with use of other libs; use /NODEFAULTLIB:library
..\bin\Release\Game.exe : fatal error LNK1169: one or more multiply defined symbols found