#include <string>

std::string ws2s(const std::wstring& ws)
{
    std::string curLocale = setlocale(LC_ALL, NULL);        // curLocale = "C";
    setlocale(LC_ALL, "chs");
    const wchar_t* _Source = ws.c_str();
    size_t _Dsize = 2 * ws.size() + 1;
    char *_Dest = new char[_Dsize];
    memset(_Dest,0,_Dsize);
    wcstombs(_Dest,_Source,_Dsize);
    std::string result = _Dest;
    delete []_Dest;
    setlocale(LC_ALL, curLocale.c_str());
    return result;
}

std::wstring s2ws(const std::string& s)
{
    setlocale(LC_ALL, "chs"); 
    const char* _Source = s.c_str();
    size_t _Dsize = s.size() + 1;
    wchar_t *_Dest = new wchar_t[_Dsize];
    wmemset(_Dest, 0, _Dsize);
    mbstowcs(_Dest,_Source,_Dsize);
    std::wstring result = _Dest;
    delete []_Dest;
    setlocale(LC_ALL, "C");
    return result;
}

//c++ string 和wstring 之间的互相转换函数:
string a = "xxxx";
wstring b(a.begin(), a.end());