PHP获取中文汉字首字母方法

function getFirstLetter($str){
	$fchar = ord($str{0});
	if($fchar >= ord("A") and $fchar <= ord("z") )return strtoupper($str{0});
	$s1 = iconv("UTF-8","gb2312", $str);
	$s2 = iconv("gb2312","UTF-8", $s1);
	if($s2 == $str){$s = $s1;}
	else{$s = $str;}
	$asc = ord($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 $asc <= -17418) return "I";
	if($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 >= -12556 and $asc <= -11848) return "X";
	if($asc >= -11847 and $asc <= -11056) return "Y";
	if($asc >= -11055 and $asc <= -10247) return "Z";
	return null;
}