PHP开发中如何获取英文首字母

/** 
  * 
  */ 
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 = -20319 and $asc = -20283 and $asc = -19775 and $asc = -19218 and $asc = -18710 and $asc = -18526 and $asc = -18239 and $asc = -17922 and $asc = -17417 and $asc = -16474 and $asc = -16212 and $asc = -15640 and $asc = -15165 and $asc = -14922 and $asc = -14914 and $asc = -14630 and $asc = -14149 and $asc = -14090 and $asc = -13318 and $asc = -12838 and $asc = -12556 and $asc = -11847 and $asc = -11055 and $asc