ConvertUnicodeToUTF8

CStringA ConvertUnicodeToUTF8(const CStringW& uni)
{
    if (uni.IsEmpty()) return ""; // nothing to do

    CStringA utf8;
    int cc = 0;

    // get length (cc) of the new multibyte string excluding the \0 terminator first
    if ((cc = WideCharToMultiByte(CP_UTF8, 0, uni, -1, NULL, 0, 0, 0) - 1) > 0)
    {
        // convert
        char* buf = utf8.GetBuffer(cc);
        if (buf) WideCharToMultiByte(CP_UTF8, 0, uni, -1, buf, cc, 0, 0);
        utf8.ReleaseBuffer();
    }
    return utf8;
}