Hi all, Today I met an link problem after updating the VS version from 2008 to 2010, the error is something like this: error LNK2019: unresolved external symbol "public: static void __cdecl std::_String_base::_Xran(void)" (?_Xran@_String_base@std@@SAXXZ) referenced in function "public: class std::basic_string,class std::allocator & __thiscall std::basic_string,class std::allocator ::assign(class std::basic_string,class std::allocator const &,unsigned int,unsigned int)" (?assign@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAEAAV12@ABV12@II@Z) error LNK2019: unresolved external symbol "public: static void __cdecl std::_String_base::_Xlen(void)" (?_Xlen@_String_base@std@@SAXXZ) referenced in function "protected: bool __thiscall std::basic_string,class std::allocator ::_Grow(unsigned int,bool)" (?_Grow@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@IAE_NI_N@Z) I have googled this issue on the web, and found a similar post in this address : http://social.msdn.microsoft.com/Forums/en/vcgeneral/thread/5ac28a31-3339-4db1-90f4-68edad360309 But none of these answers can solve my problem. Could anyone give me some tips on how to solve this issue? Thanks a lot for the help!