用PHP提取中英文词语以及数字的首字母的方法介绍

最近项目有个需求，在一个中英文（包括阿拉伯数字0-9）的海量词库中，提取每一个词语的首字母：

gannicus——>g

*自在——>z

2b——>e

傻x——>s

private function getfirstchar($s0){
        $s=iconv('utf-8','gb2312', $s0);
        if (ord($s0)>128) { //汉字开头
            $asc=ord($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 $asc<=-10247)return "z"; 
        }else if(ord($s)>=48 and ord($s)<=57){ //数字开头
            switch(iconv_substr($s,0,1,'utf-8'))
            {
                case 1:return "y";
                case 2:return "e";
                case 3:return "s";
                case 4:return "s";
                case 5:return "w";
                case 6:return "l";
                case 7:return "q";
                case 8:return "b";
                case 9:return "j";
                case 0:return "l";
            }               
        }else if(ord($s)>=65 and ord($s)<=90){ //大写英文开头
            return substr($s,0,1);
        }else if(ord($s)>=97 and ord($s)<=122){ //小写英文开头
            return strtoupper(substr($s,0,1));
        }
        else
        {
            return iconv_substr($s0,0,1,'utf-8');//中英混合的词语，不适合上面的各种情况，因此直接提取首个字符即可
        }

    }

遗留问题：仍有少量词语无法提取，如亘古不灭，的g 没有提取出来

最终效果如图：