php根据传入的汉字（str）得出收个字母

function getinitial($str) {
if (empty($str)) {return '';}
$fchar = ord($str{0});
if ($fchar >= ord('A') && $fchar <= ord('z')) return strtoupper($str{0});
$s1 = iconv('UTF-8','gb2312',$str);
$s2 = iconv('gb2312','UTF-8',$s1);
$s = $s2 == $str?$s1:$str;
$asc = ord($s{0})*256 + ord($s{1})-65536;
if ($str == "讴歌")
$asc = -14921;
if ($str == "阿斯顿·马丁")
$asc = -20319;

if($asc >= -20319&&$asc <= -20284) return 'A';
if($asc >= -20283&&$asc <= -19776) return 'B';
if($asc >= -19775&&$asc <= -19219) return 'C';
if($asc >= -19218&&$asc <= -18711) return 'D';
if($asc >= -18710&&$asc <= -18527) return 'E';
if($asc >= -18526&&$asc <= -18240) return 'F';
if($asc >= -18239&&$asc <= -17923) return 'G';
if($asc >= -17922&&$asc <= -17418) return 'H';
if($asc >= -17417&&$asc <= -16475) return 'J';
if($asc >= -16474&&$asc <= -16213) return 'K';
if($asc >= -16212&&$asc <= -15641) return 'L';
if($asc >= -15640&&$asc <= -15166) return 'M';
if($asc >= -15165&&$asc <= -14923) return 'N';
if($asc >= -14922&&$asc <= -14915) return 'O';
if($asc >= -14914&&$asc <= -14631) return 'P';
if($asc >= -14630&&$asc <= -14150) return 'Q';
if($asc >= -14149&&$asc <= -14091) return 'R';
if($asc >= -14090&&$asc <= -13319) return 'S';
if($asc >= -13318&&$asc <= -12839) return 'T';
if($asc >= -12838&&$asc <= -12557) return 'W';
if($asc >= -12556&&$asc <= -11848) return 'X';
if($asc >= -11847&&$asc <= -11056) return 'Y';
if($asc >= -11055&&$asc <= -10247) return 'Z';
return null;
}

}