PHP

Mask credit card number in PHP

function ccMasking($number, $maskingCharacter = 'X') {
    return substr($number, 0, 4) . str_repeat($maskingCharacter, strlen($number) - 8) . substr($number, -4);
}

php mask credit card number

return substr_replace($creditCardNumber, str_repeat("X", 8), 4, 8);