PHP を解析してタイトルのピンインの最初の文字を取得します (コード例付き)

    public function getfirstchar($s0)
    {
        $fchar = ord($s0{0});
        if($fchar >= ord("A") and $fchar <= ord("z") ) return strtoupper($s0{0});
        $s1 = mb_convert_encoding($s0,"GBK","UTF-8");//iconv("UTF-8","GBK", $s0);
        $s2 = mb_convert_encoding($s1,"UTF-8","GBK");//iconv("GBK","UTF-8", $s1);
        if($s2 == $s0){$s = $s1;}else{$s = $s0;}
        $asc = ord($s{0}) * 256 + ord($s{1}) - 65536;
        if($asc >= -20319 and $asc <= -20284) return "a";
        if($asc >= -20283 and $asc <= -19776) return "b";
        if($asc >= -19775 and $asc <= -19219) return "c";
        if($asc >= -19218 and $asc <= -18711) return "d";
        if($asc >= -18710 and $asc <= -18527) return "e";
        if($asc >= -18526 and $asc <= -18240) return "f";
        if($asc >= -18239 and $asc <= -17923) return "g";
        if($asc >= -17922 and $asc <= -17418) return "h";
        if($asc >= -17922 and $asc <= -17418) return "i";
        if($asc >= -17417 and $asc <= -16475) return "j";
        if($asc >= -16474 and $asc <= -16213) return "k";
        if($asc >= -16212 and $asc <= -15641) return "l";
        if($asc >= -15640 and $asc <= -15166) return "m";
        if($asc >= -15165 and $asc <= -14923) return "n";
        if($asc >= -14922 and $asc <= -14915) return "o";
        if($asc >= -14914 and $asc <= -14631) return "p";
        if($asc >= -14630 and $asc <= -14150) return "q";
        if($asc >= -14149 and $asc <= -14091) return "r";
        if($asc >= -14090 and $asc <= -13319) return "s";
        if($asc >= -13318 and $asc <= -12839) return "t";
        if($asc >= -12838 and $asc <= -12557) return "w";
        if($asc >= -22605 and $asc <= -11848) return "x";
        if($asc >= -11847 and $asc <= -11056) return "y";
        if($asc >= -11055 and $asc <= -10247) return "z";
        return NULL;
    }