Php Iban Check

<?php
 
// CopyLeft  javam.org tarafından yayınlanmıştır.
 
function ibanDogrula ($deger) {
    $iban = false;
    $deger = strtoupper(trim($deger));
    if(preg_match('/^TR\d{7}0[A-Z0-9]{16}$/', $deger)) {
        $sayi = substr($deger,4,22).'2927'.substr($deger,2,2);
        $sayi = str_replace(
            array('A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'),
            array(10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35),
            $sayi
        );
        $iban = (1 == bcmod($sayi,97)) ? true:false;
    }
return $iban;
}