php判斷漢字首字母

<?

function getfirstletter($string) {

   global $encoding;

   if($encoding=='UTF-8'){

    $string=string::hiconv($string,'gbk','utf-8');

   }

   $dict=array(

    'a'=>0xB0C4,'b'=>0xB2C0,'c'=>0xB4ED,'d'=>0xB6E9,

    'e'=>0xB7A1,'f'=>0xB8C0,'g'=>0xB9FD,'h'=>0xBBF6,

    'j'=>0xBFA5,'k'=>0xC0AB,'l'=>0xC2E7,'m'=>0xC4C2,

    'n'=>0xC5B5,'o'=>0xC5BD,'p'=>0xC6D9,'q'=>0xC8BA,

    'r'=>0xC8F5,'s'=>0xCBF9,'t'=>0xCDD9,'w'=>0xCEF3,

    'x'=>0xD1B8,'y'=>0xD4D0,'z'=>0xD7F9,

    );

   $letter = substr($string, 0, 1);

   $letter_ord = ord($letter);

   if($letter_ord >= 176 && $letter_ord <= 215){

    $num = '0x'.bin2hex(substr($string, 0, 2));

    foreach ($dict as $k=>$v){

     if($v>=$num) break;

    }

    return $k;

   }elseif(($letter_ord>64 && $letter_ord<91) || ($letter_ord>96 && $letter_ord<123)){

    return $letter;

   }elseif($letter>='0' && $letter<='9'){

    return $letter;

   }else{

    return '*';

   }

}

echo getfirstletter("你好，我是大山。");

?>