json \u unicode字符串转化 c++

CString GetUStr(const string & str)
{
    std::string showname = str;//\u6211\u7231\u5317\u4eac\u5929\u5b89\u95e8
    int len=strlen(showname.c_str())+;
    char outch[MAX_PATH];
    WCHAR * wChar=new WCHAR[len];
    wmemset(wChar,,len);
    MultiByteToWideChar(CP_UTF8, , showname.c_str(), len, wChar, len);
    CString strRet = wChar;//转化结果 我爱北京天安门
    delete [] wChar;
    return strRet;
}