php - จะนับเฉพาะ a-z กับ 0-9 ยังไงคะ

<?php

$chr = "!E@s#f$%^&csdf*faa(W)d";

$i = 0;
foreach(str_split($chr) as $val){
    
    $in = str_split("ABCDEFGHIJKLMNOPQRXYZabcdefghijklmnopqrxyz0123456789");
    
    foreach($in as $kk){
        if($val == $kk){
            //echo $val.":".$kk."</br>";
            ++$i;
        }
    }
    
}

echo $i;
?>