PHP提取中英文詞語以及數字的首字母

最近項目有個需求，在一箇中英文（包括阿拉伯數字0-9）的海量詞庫中，提取每一個詞語的首字母：

gannicus——>G

自由自在——>Z

2B——>E

傻X——>S

private function getfirstchar($s0){
        $s=iconv('UTF-8','gb2312', $s0);
        if (ord($s0)>128) { //漢字開頭
            $asc=ord($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($s)<=57){ //數字開頭
            switch(iconv_substr($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){ //大寫英文開頭
            return substr($s,0,1);
        }else if(ord($s)>=97 and ord($s)<=122){ //小寫英文開頭
            return strtoupper(substr($s,0,1));
        }
        else
        {
            return iconv_substr($s0,0,1,'utf-8');//中英混合的詞語，不適合上面的各種情況，因此直接提取首個字符即可
        }
        
    }

遺留問題：仍有少量詞語無法提取，如亙古不滅，的G 沒有提取出來

最終效果如圖：