使用Visual Studio 2013编译C ++程序时，出现错误：
1)Error 49 error LNK2001: unresolved external symbol "void __cdecl std::_Xlen(void)" (?_Xlen@std@@YAXXZ)
2)Error 50 error LNK2001: unresolved external symbol "void __cdecl std::_Xlen(void)" (?_Xlen@std@@YAXXZ)
3)Error 48 error LNK2019: unresolved external symbol "void __cdecl std::_Xlen(void)" (?_Xlen@std@@YAXXZ) referenced in function "public: class std::basic_string<unsigned short,struct std::char_traits<unsigned short>,class std::allocator<unsigned short> > & __thiscall std::basic_string<unsigned short,struct std::char_traits<unsigned short>,class std::allocator<unsigned short> >::append(unsigned short const *,unsigned int)" (?append@?$basic_string@GU?$char_traits@G@std@@V?$allocator@G@2@@std@@QAEAAV12@PBGI@Z)
4)Error 47 error LNK2019: unresolved external symbol "void __cdecl std::_Xran(void)" (?_Xran@std@@YAXXZ) referenced in function "public: class std::basic_string<unsigned short,struct std::char_traits<unsigned short>,class std::allocator<unsigned short> > & __thiscall std::basic_string<unsigned short,struct std::char_traits<unsigned short>,class std::allocator<unsigned short> >::assign(class std::basic_string<unsigned short,struct std::char_traits<unsigned short>,class std::allocator<unsigned short> > const &,unsigned int,unsigned int)" (?assign@?$basic_string@GU?$char_traits@G@std@@V?$allocator@G@2@@std@@QAEAAV12@ABV12@II@Z)
我在网上搜索过这个问题，但没有一个答案可以解决我的问题。谁能给我一些如何解决这个问题的技巧？
感谢您的帮助！