Check IBAN number

iban.php

<?php
/**
 * Value should be an IBAN number
 *
 *
 * @param   string
 * @return  bool
 */
function iban($str)
{
    $CountryCodes = [
        'al'=>28,'ad'=>24,'at'=>20,'az'=>28,'bh'=>22,'be'=>16,'ba'=>20,'br'=>29,'bg'=>22,'cr'=>21,'hr'=>21,'cy'=>28,'cz'=>24,
        'dk'=>18,'do'=>28,'ee'=>20,'fo'=>18,'fi'=>18,'fr'=>27,'ge'=>22,'de'=>22,'gi'=>23,'gr'=>27,'gl'=>18,'gt'=>28,'hu'=>28,
        'is'=>26,'ie'=>22,'il'=>23,'it'=>27,'jo'=>30,'kz'=>20,'kw'=>30,'lv'=>21,'lb'=>28,'li'=>21,'lt'=>20,'lu'=>20,'mk'=>19,
        'mt'=>31,'mr'=>27,'mu'=>30,'mc'=>27,'md'=>24,'me'=>22,'nl'=>18,'no'=>15,'pk'=>24,'ps'=>29,'pl'=>28,'pt'=>25,'qa'=>29,
        'ro'=>24,'sm'=>27,'sa'=>24,'rs'=>22,'sk'=>24,'si'=>19,'es'=>24,'se'=>24,'ch'=>21,'tn'=>24,'tr'=>26,'ae'=>23,'gb'=>22,
        'vg'=>24];
    $Chars = [
        'a'=>10,'b'=>11,'c'=>12,'d'=>13,'e'=>14,'f'=>15,'g'=>16,'h'=>17,'i'=>18,'j'=>19,'k'=>20,'l'=>21,'m'=>22,
        'n'=>23,'o'=>24,'p'=>25,'q'=>26,'r'=>27,'s'=>28,'t'=>29,'u'=>30,'v'=>31,'w'=>32,'x'=>33,'y'=>34,'z'=>35
        ];
    $str    = str_replace(' ','',strip_tags($str));
    $iban   = strtolower($str);
    if(isset($CountryCodes[substr($iban,0,2)]) && strlen($str) == $CountryCodes[substr($iban,0,2)]) {
        //Rearrange
        $iban = substr($iban, 4).substr($iban, 0, 4);
        //Replace
        $iban = str_replace(array_keys($Chars), array_values($Chars), $iban);
        return(bcmod($iban, '97') == 1);
    }
    return FALSE;
}
?>