// Create and display a C style string, and then use it 
    // to create different kinds of strings.
    char *orig = "Hello, World!";
    cout << orig << " (char *)" << endl;
 
    // newsize describes the length of the 
    // wchar_t string called wcstring in terms of the number 
    // of wide characters, not the number of bytes.
    size_t newsize = strlen(orig) + 1;
 
    // The following creates a buffer large enough to contain 
    // the exact number of characters in the original string
    // in the new format. If you want to add more characters
    // to the end of the string, increase the value of newsize
    // to increase the size of the buffer.
    wchar_t * wcstring = new wchar_t[newsize];
 
    // Convert char* string to a wchar_t* string.
    size_t convertedChars = 0;
    mbstowcs_s(&convertedChars, wcstring, newsize, orig, _TRUNCATE);
    // Display the result and indicate the type of string that it is.
    wcout << wcstring << _T(" (wchar_t *)") << endl;

errno_t mbstowcs_s(
   size_t *pReturnValue,
   wchar_t *wcstr,
   size_t sizeInWords,
   const char *mbstr,
   size_t count 
);

    // 計算輸入(欲轉換)字串 pszValue 的字數 (character)。注意! 非字節數 (byte)。
    size_t n = ::MultiByteToWideChar(CP_ACP,0,(const char *)pszValue,-1,NULL,0);
 
    // 配置輸出(欲轉出)字串緩衝區。
    wchar_t* buffer = new wchar_t[n];
 
    // 轉換輸入字串 (pszValue) 至輸出字串緩衝區 (buffer)。
    ::MultiByteToWideChar(CP_ACP,0,(const char *)pszValue,-1,buffer,int(n));
 
    // 將緩衝區資料另存起來。
    m_strValue = tstring(buffer);
 
    // 釋放緩衝區。
    delete [] buffer;

int MultiByteToWideChar(
  _In_       UINT CodePage,
  _In_       DWORD dwFlags,
  _In_       LPCSTR lpMultiByteStr,
  _In_       int cbMultiByte,
  _Out_opt_  LPWSTR lpWideCharStr,
  _In_       int cchWideChar
);

#include <sstream>
#include "tstring.h"
 
std::wstringstream wss;
wss << pszValue;
m_strValue = tstring(wss.str().c_str());