errno_t wcstombs_s(
   size_t *pReturnValue, //被修改的位数，作为返回的
   char *mbstr,          //转换后字符串（窄）的空间指针
   size_t sizeInBytes,   //我暂时理解为，允许操作窄字符缓冲区的字符的个数，

                         //要比count大1，不能大过缓冲区最大长度
   const wchar_t *wcstr,  //指向要转换的宽字符字符串
   size_t count ) ;         //要转换的宽字符的个数;

//窄字符转换为宽字符

errno_t mbstowcs_s(
   size_t *pReturnValue, //被修改的位数，作为返回的 

   wchar_t *wcstr,       //转换后宽字符串的缓冲区指针
   size_t sizeInWords,   // 允许操作缓冲区中宽字符的个数
   const char *mbstr,    //指向要转换的窄字符的字符串
   size_t count          //要转换的窄字符的个数
);

   1:  #include <string>

   2:  #include <cstdlib>

   3:   

   4:  std::string ws2s(const std::wstring& ws)

   5:  {

   6:      std::string curLocale = setlocale(LC_ALL, NULL);        // curLocale = "C";

   7:      setlocale(LC_ALL, "chs");                                             //中文地区

   8:      const wchar_t* _Source = ws.c_str();

   9:      size_t _Dsize =  ws.size() + 1;                                    //比要转换的宽字符个数大1

  10:      char *_Dest = new char[_Dsize];

  11:      memset(_Dest, 0, _Dsize);                                          //初始化缓冲区

  12:      size_t   i;

  13:      wcstombs_s(&i, _Dest, _Dsize, _Source, ws.size());

  14:      std::cout << "i:" << i << std::endl;                          

  15:      std::string result = _Dest;

  16:      delete[]_Dest;

  17:      setlocale(LC_ALL, curLocale.c_str());                               //设置回原来的locale

  18:      return result;

  19:  }

   1:  std::wstring s2ws(const std::string& s)

   2:  {

   3:      std::string curlLocale = setlocale(LC_ALL,NULL);

   4:      setlocale(LC_ALL, "chs");

   5:      const char* _Source = s.c_str();

   6:      size_t _Dsize = s.size() + 1;

   7:   

   8:      wchar_t* _Dest = new wchar_t[_Dsize];

   9:      size_t i;

  10:      mbstowcs_s(&i, _Dest, _Dsize, _Source, s.size());

  11:      std::wstring result = _Dest;

  12:      delete[] _Dest;

  13:      setlocale(LC_ALL, curlLocale.c_str());

  14:      return result;

  15:  }