UTF8 to ASCII & ASCII to UTF8

string UTF82ASCII(const char* cont)
{
    if (NULL == cont)
    {
        return string("");
    }
    int num = MultiByteToWideChar(CP_UTF8, NULL, cont, -1, NULL, NULL);
    wchar_t* buffw = new wchar_t[(unsigned int)num];
    MultiByteToWideChar(CP_UTF8, NULL, cont, -1, buffw, num);
    int len = WideCharToMultiByte(CP_ACP, 0, buffw, num - 1, NULL, NULL, NULL, NULL); 
    char* lpsz = new char[(unsigned int)len + 1]; 
    WideCharToMultiByte(CP_ACP, 0, buffw, num - 1, lpsz, len, NULL, NULL);
    lpsz[len]='\0';
    delete[] buffw;
    string rtn(lpsz);
    delete[] lpsz;
    return rtn ;  
}

/*********************************************************
函數名:	A2UTF8
函數描述:	多字節轉UTF8
輸入參數:	cont - 多字節字符串                       
輸出參數:	
返回值:	    UTF8編碼的字符串
**********************************************************/
string ASCII2UTF8(const char* cont)
{
    if (NULL == cont)
    {
        return string("");
    }
    
    int num = MultiByteToWideChar(CP_ACP, NULL, cont, -1, NULL, NULL);
    wchar_t* buffw = new wchar_t[(unsigned int)num];
    MultiByteToWideChar(CP_ACP, NULL, cont, -1, buffw, num);
    
    int len = WideCharToMultiByte(CP_UTF8, 0, buffw, num - 1, NULL, NULL, NULL, NULL); 
    char* lpsz = new char[(unsigned int)len + 1]; 
    WideCharToMultiByte(CP_UTF8, 0, buffw, num - 1, lpsz, len, NULL, NULL);
    lpsz[len]='\0';
    delete[] buffw;
    
    string rtn(lpsz);
    delete[] lpsz;
    return rtn;
}