unicode转UTF8

static CFStringA UniToUTF8(const CFStringW& pUniString)
{
int nLen = WideCharToMultiByte(CP_UTF8, 0, pUniString, -1, NULL, 0, NULL, NULL); 
char *szUtf8Temp = new char[nLen + 1];
memset( szUtf8Temp, 0, nLen + 1 ); 
WideCharToMultiByte ( CP_UTF8, 0, pUniString, -1, szUtf8Temp, nLen, NULL, NULL ); 
CFStringA strUtf8 = szUtf8Temp;
delete[] szUtf8Temp; 
return strUtf8;
}