IBAN korrekt prüfen

Dieses PHP Codeschnipsel prüft IBAN Nummern zuverlässig nach Länderkennung, korrekter Länge und offizieller Prüfsummenlogik. Durch die hinterlegte Ländertabelle werden fehlerhafte oder unvollständige IBANs frühzeitig erkannt. Die Modulo 97-Berechnung sorgt für eine bankkonforme Validierung. Ideal für Formulare, Zahlungsprozesse und interne Prüfungen

function isValidIBAN(string $iban): bool
{
    $iban = strtoupper(str_replace(' ', '', $iban));
    if (!preg_match('/^[A-Z0-9]+$/', $iban)) {
        return false;
    }
    $countryCode = substr($iban, 0, 2);
    $ibanLengths = [
        'AL' => 28, 'AD' => 24, 'AT' => 20, 'AZ' => 28, 'BE' => 16, 'BH' => 22,
        'BA' => 20, 'BR' => 29, 'BG' => 22, 'CR' => 21, 'HR' => 21, 'CY' => 28,
        'CZ' => 24, 'DK' => 18, 'DO' => 28, 'EE' => 20, 'FO' => 18, 'FI' => 18,
        'FR' => 27, 'GE' => 22, 'DE' => 22, 'GI' => 23, 'GR' => 27, 'GL' => 18,
        'GT' => 28, 'HU' => 28, 'IS' => 26, 'IE' => 22, 'IL' => 23, 'IT' => 27,
        'KZ' => 20, 'KW' => 30, 'LV' => 21, 'LB' => 28, 'LI' => 21, 'LT' => 20,
        'LU' => 20, 'MK' => 19, 'MT' => 31, 'MR' => 27, 'MU' => 30, 'MC' => 27,
        'MD' => 24, 'ME' => 22, 'NL' => 18, 'NO' => 15, 'PK' => 24, 'PS' => 29,
        'PL' => 28, 'PT' => 25, 'RO' => 24, 'SM' => 27, 'SA' => 24, 'RS' => 22,
        'SK' => 24, 'SI' => 19, 'ES' => 24, 'SE' => 24, 'CH' => 21, 'TN' => 24,
        'TR' => 26, 'AE' => 23, 'GB' => 22, 'VG' => 24
    ];
    if (!isset($ibanLengths[$countryCode])) {
        return false;
    }
    if (strlen($iban) !== $ibanLengths[$countryCode]) {
        return false;
    }
    $rearranged = substr($iban, 4) . substr($iban, 0, 4);
    $numericIban = '';
    foreach (str_split($rearranged) as $char) {
        if (ctype_alpha($char)) {
            $numericIban .= ord($char) - 55;
        } else {
            $numericIban .= $char;
        }
    }
    $remainder = 0;
    foreach (str_split($numericIban) as $digit) {
        $remainder = ($remainder * 10 + (int)$digit) % 97;
    }
    return $remainder === 1;
}