PHP实现提取中英文首字母的方法

/** 
  * 
  */ 
function getfirstchar($s0){ 
        if($s0[0]=='I' || $s[0]=='i'){ 
          return "I"; 
        }elseif($s0[0]=='U' || $s[0]=='u'){ 
          return 'U'; 
        }elseif($s0[0]=='V' || $s[0]=='v'){ 
          return 'V'; 
        }else{ 
  $fchar = ord($s0{0}); 
  if($fchar >= ord("A") and $fchar <= ord("z") )return strtoupper($s0{0}); 
  $s1 = iconv("UTF-8","gb2312", $s0); 
  $s2 = iconv("gb2312","UTF-8", $s1); 
  if($s2 == $s0){$s = $s1;}else{$s = $s0;} 
  $asc = ord($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 $asc <= -17418) return "H"; 
  if($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"; 
  return null; 
        } 
  }