windows 编码
这里的多字节，通常对应vs的多字节，一般就是gbk和ansi

bool Unicode2UTF(vector<char> &Dest, wchar_t *szSrc)
{
    if(szSrc == NULL)
        return false;
    int iTextLen = wcslen(szSrc);
    if (iTextLen == 0)
    {
        return false;
    }
    char*     pElementText;
    iTextLen = WideCharToMultiByte( CP_UTF8,
        0,
        (LPWSTR)szSrc,
        -1,
        NULL,
        0,
        NULL,
        NULL );
    if(iTextLen==0)
        return false;
    Dest.resize(iTextLen);
    ::WideCharToMultiByte( CP_UTF8,
        0,
        (LPWSTR)szSrc,
        -1,
        &*Dest.begin(),
        iTextLen,
        NULL,
        NULL );
    return true;

}
bool UTF2Unicode(vector<wchar_t> &Dest,const char *szSrc)
{
    int  iTextLen=strlen(szSrc);
    if(iTextLen == 0)
    {
        return false;
    }
    char*     pElementText;
    //MultiByteToWideChar(CP_UTF8, NULL, szU8, strlen(szU8), NULL, 0);

    iTextLen = MultiByteToWideChar(CP_UTF8, NULL, szSrc, strlen(szSrc),NULL,0 );
    if(iTextLen==0)
        return false;
    Dest.resize(iTextLen);
    ::MultiByteToWideChar (CP_UTF8, 0, szSrc, -1, (LPWSTR)&*Dest.begin(), iTextLen); 
    return true;
}

// 多字节编码转为Unicode编码  
bool MBToUnicode(vector<wchar_t>& pun, const char* pmb, int mLen)  
{  
    // convert an MBCS string to widechar   
    int uLen = MultiByteToWideChar(CP_ACP, 0, pmb, mLen, NULL, 0);  
    
    if (uLen<=0)  
    {  
        return false;  
    }  
    pun.resize(uLen);  
    
    int nRtn = MultiByteToWideChar(CP_ACP, 0, pmb, mLen, &*pun.begin(), uLen);  
    
    if (nRtn != uLen)  
    {  
        pun.clear();  
        return false;  
    }  
    return true;  
} 
//Unicode编码转为多字节编码  
bool  UnicodeToMB(vector<char>& pmb, const wchar_t* pun, int uLen)  
{  
    // convert an widechar string to Multibyte   
    int MBLen = WideCharToMultiByte(CP_ACP, 0, pun, uLen, NULL, 0, NULL, NULL);  
    if (MBLen <=0)  
    {  
        return false;  
    }  
    pmb.resize(MBLen);  
    int nRtn = WideCharToMultiByte(CP_ACP, 0, pun, uLen, &*pmb.begin(), MBLen, NULL, NULL);  
  
    if(nRtn != MBLen)  
    {  
        pmb.clear();  
        return false;  
    }  
    return true;  
}