PHP获取字符串的第一个中文的首字母

private function firstLeter($str){ 

            $str= iconv("UTF-8","gb2312", $str);//如果程序是gbk的，此行就要注释掉  

            //判断字符串是否全都是中文 

            if (preg_match("/^[\x7f-\xff]/", $str)){ 

                $fchar=ord($str{0}); 

                if($fchar>=ord("A") and $fchar<=ord("z") )return strtoupper($str{0});

               

                $val=ord($str{0})*256+ord($str{1})-65536; 

                   

                if($val>=-20319 and $val<=-20284)return "A"; 

                   

                if($val>=-20283 and $val<=-19776)return "B";

                   

                if($val>=-19775 and $val<=-19219)return "C"; 

                   

                if($val>=-19218 and $val<=-18711)return "D"; 

                   

                if($val>=-18710 and $val<=-18527)return "E";

                   

                if($val>=-18526 and $val<=-18240)return "F"; 

                   

                if($val>=-18239 and $val<=-17923)return "G";

                   

                if($val>=-17922 and $val<=-17418)return "H";

                   

                if($val>=-17417 and $val<=-16475)return "J";

                   

                if($val>=-16474 and $val<=-16213)return "K";

                   

                if($val>=-16212 and $val<=-15641)return "L";

                   

                if($val>=-15640 and $val<=-15166)return "M";

                   

                if($val>=-15165 and $val<=-14923)return "N";

                   

                if($val>=-14922 and $val<=-14915)return "O";

                   

                if($val>=-14914 and $val<=-14631)return "P"; 

                   

                if($val>=-14630 and $val<=-14150)return "Q"; 

                   

                if($val>=-14149 and $val<=-14091)return "R";

                   

                if($val>=-14090 and $val<=-13319)return "S";

                   

                if($val>=-13318 and $val<=-12839)return "T";

                   

                if($val>=-12838 and $val<=-12557)return "W"; 

                   

                if($val>=-12556 and $val<=-11848)return "X";

                   

                if($val>=-11847 and $val<=-11056)return "Y";

                   

                if($val>=-11055 and $val<=-10247)return "Z";  
 

            }else{   

                return '不是中文!';

         }   

    }