PHP获取汉字拼音首字母函数

<!--?php
/**
 * @param unknown_type $str
 * @return 取得汉字的首字母
 */
function getfirstchar($str){   
 $fchar=$str[0];
 //判断是否为字符串
 if(ord($fchar)-->=ord("A") && ord($fchar)<=ord("z") )
  return strtoupper($fchar);
 $str=iconv("UTF-8","gb2312", $str);   
 $asc=ord($str[0])*256+ord($str[1])-65536;   
 if($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 $asc<=-16475)return "I";                 
 if($asc>=-16474 and $asc<=-16213)return "J";                 
 if($asc>=-16212 and $asc<=-15641)return "K";                 
 if($asc>=-15640 and $asc<=-15166)return "L";                 
 if($asc>=-15165 and $asc<=-14923)return "M";                 
 if($asc>=-14922 and $asc<=-14915)return "N";                 
 if($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;   
}
echo getfirstchar("哈哈!");