PHP获取中文首字母函数

function getFirstChar($zh_cn) {    $firsh_zh = mb_substr($zh_cn, 0, 1);    $fchar = ord($firsh_zh{0});    if ($fchar >= ord("A") && $fchar <= ord("z")) {        return strtoupper($firsh_zh{0});    }    $s1 = iconv("UTF-8", "gb2312", $firsh_zh);    $s2 = iconv("gb2312", "UTF-8", $s1);    if ($s2 == $firsh_zh) {        $s = $s1;    } else {        $s = $firsh_zh;    }    $asc = ord($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 >= -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;}