PHP常用函数之获取汉字首字母功能示例

 //获取汉字的首字母
    public   function getFirstCharters($str)
    {
        if (empty($str)) {
            return '';
        }
        //取出参数字符串中的首个字符
        $temp_str = substr($str,0,1);
        if(ord($temp_str) > 127){
            $str = substr($str,0,3);
        }else{
            $str = $temp_str;
            $fchar = ord($str{0});
            if ($fchar >= ord('A') && $fchar <= ord('z')){
                return strtoupper($temp_str);
            }else{
                return null;
            }
        }
        $s1 = iconv('UTF-8', 'gb2312//IGNORE', $str);
        if(empty($s1)){
            return null;
        }
        $s2 = iconv('gb2312', 'UTF-8', $s1);
        if(empty($s2)){
            return null;
        }
        $s = $s2 == $str ? $s1 : $str;
        $asc = ord($s{0}) * 256 + ord($s{1}) - 65536;
        if ($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  $this->rare_words($asc);
    }
//百家姓中的生僻字
    function rare_words($asc=''){
        $rare_arr = array(
            -3652=>array('word'=>"窦",'first_char'=>'D'),
            -8503=>array('word'=>"奚",'first_char'=>'X'),
            -9286=>array('word'=>"酆",'first_char'=>'F'),
            -7761=>array('word'=>"岑",'first_char'=>'C'),
            -5128=>array('word'=>"滕",'first_char'=>'T'),
            -9479=>array('word'=>"邬",'first_char'=>'W'),
            -5456=>array('word'=>"臧",'first_char'=>'Z'),
            -7223=>array('word'=>"闵",'first_char'=>'M'),
            -2877=>array('word'=>"裘",'first_char'=>'Q'),
            -6191=>array('word'=>"缪",'first_char'=>'M'),
            -5414=>array('word'=>"贲",'first_char'=>'B'),
            -4102=>array('word'=>"嵇",'first_char'=>'J'),
            -8969=>array('word'=>"荀",'first_char'=>'X'),
            -4938=>array('word'=>"於",'first_char'=>'Y'),
            -9017=>array('word'=>"芮",'first_char'=>'R'),
            -2848=>array('word'=>"羿",'first_char'=>'Y'),
            -9477=>array('word'=>"邴",'first_char'=>'B'),
            -9485=>array('word'=>"隗",'first_char'=>'K'),
            -6731=>array('word'=>"宓",'first_char'=>'M'),
            -9299=>array('word'=>"郗",'first_char'=>'X'),
            -5905=>array('word'=>"栾",'first_char'=>'L'),
            -4393=>array('word'=>"钭",'first_char'=>'T'),
            -9300=>array('word'=>"郜",'first_char'=>'G'),
            -8706=>array('word'=>"蔺",'first_char'=>'L'),
            -3613=>array('word'=>"胥",'first_char'=>'X'),
            -8777=>array('word'=>"莘",'first_char'=>'S'),
            -6708=>array('word'=>"逄",'first_char'=>'P'),
            -9302=>array('word'=>"郦",'first_char'=>'L'),
            -5965=>array('word'=>"璩",'first_char'=>'Q'),
            -6745=>array('word'=>"濮",'first_char'=>'P'),
            -4888=>array('word'=>"扈",'first_char'=>'H'),
            -9309=>array('word'=>"郏",'first_char'=>'J'),
            -5428=>array('word'=>"晏",'first_char'=>'Y'),
            -2849=>array('word'=>"暨",'first_char'=>'J'),
            -7206=>array('word'=>"阙",'first_char'=>'Q'),
            -4945=>array('word'=>"殳",'first_char'=>'S'),
            -9753=>array('word'=>"夔",'first_char'=>'K'),
            -10041=>array('word'=>"厍",'first_char'=>'S'),
            -5429=>array('word'=>"晁",'first_char'=>'C'),
            -2396=>array('word'=>"訾",'first_char'=>'Z'),
            -7205=>array('word'=>"阚",'first_char'=>'K'),
            -10049=>array('word'=>"乜",'first_char'=>'N'),
            -10015=>array('word'=>"蒯",'first_char'=>'K'),
            -3133=>array('word'=>"竺",'first_char'=>'Z'),
            -6698=>array('word'=>"逯",'first_char'=>'L'),
            -9799=>array('word'=>"俟",'first_char'=>'Q'),
            -6749=>array('word'=>"澹",'first_char'=>'T'),
            -7220=>array('word'=>"闾",'first_char'=>'L'),
            -10047=>array('word'=>"亓",'first_char'=>'Q'),
            -10005=>array('word'=>"仉",'first_char'=>'Z'),
            -3417=>array('word'=>"颛",'first_char'=>'Z'),
            -6431=>array('word'=>"驷",'first_char'=>'S'),
            -7226=>array('word'=>"闫",'first_char'=>'Y'),
            -9293=>array('word'=>"鄢",'first_char'=>'Y'),
            -6205=>array('word'=>"缑",'first_char'=>'G'),
            -9764=>array('word'=>"佘",'first_char'=>'S'),
            -9818=>array('word'=>"佴",'first_char'=>'N'),
            -9509=>array('word'=>"谯",'first_char'=>'Q'),
            -3122=>array('word'=>"笪",'first_char'=>'D'),
            -9823=>array('word'=>"佟",'first_char'=>'T'),
        );
        if(array_key_exists($asc, $rare_arr) && $rare_arr[$asc]['first_char']){
            return $rare_arr[$asc]['first_char'] ;
        }else{
            return null;
        }
    }

测试：

echo getFirstCharters('窦');