Validacion credit card

credit_card_validation.php

/*
 * Luhn algorithm number checker - 
 * (c) 2005-2008 shaman - www.planzero.org * This code has been released 
 * into the public domain, however please * give credit to the original author 
 * where possible.
 */
function _luhn_check($number) {
  // Strip any non-digits (useful for credit card numbers with spaces 
  // and hyphens)
	$number = preg_replace ( '/\D/', '', $number );
	
	// Set the string length and parity
	$number_length = strlen ( $number );
	$parity = $number_length % 2;
	
	// Loop through each digit and do the maths
	$total = 0;
	for($i = 0; $i < $number_length; $i ++) {
		$digit = $number [$i];
		// Multiply alternate digits by two
		if ($i % 2 == $parity) {
			$digit *= 2;
			// If the sum is two digits, add them together (in effect)
			if ($digit > 9) {
				$digit -= 9;
			}
		}
		// Total up the digits
		$total += $digit;
	}
	
	// If the total mod 10 equals 0, the number is valid
	return ($total % 10 == 0) ? TRUE : FALSE;
}

function _check_cc($cc, $extra_check = false) {
	$cards = array (
			"visa" => "(4\d{12}(?:\d{3})?)",
			// "amex" => "(3[47]\d{13})",
			// "jcb" => "(35[2-8][89]\d\d\d{10})",
			// "maestro" => "((?:5020|5038|6304|6579|6761)\d{12}(?:\d\d)?)",
			// "solo" => "((?:6334|6767)\d{12}(?:\d\d)?\d?)",
			"mastercard" => "(5[1-5]\d{14})" 
	    // "switch" => "(?:(?:(?:4903|4905|4911|4936|6333|6759)
      // \d{12})|(?:(?:564182|633110)\d{10})(\d\d)?\d?)",
		);
	$names = array (
			"Visa",
      /*"American Express", 
      "JCB", 
      "Maestro",
      "Solo", */
      "Mastercard"
      /*, "Switch"*/
  );
	$matches = array ();
	$pattern = "#^(?:" . implode ( "|", $cards ) . ")$#";
	$result = preg_match ( $pattern, str_replace ( " ", "", $cc ), $matches );
	if ($extra_check && $result > 0) {
		$result = (validatecard ( $cc )) ? 1 : 0;
	}
	return ($result > 0) ? $names [sizeof ( $matches ) - 2] : false;
}

function _validate_cvv($card_number, $cvv) {
	// Get the first number of the credit card so we know how many digits to 
  // look for
	$firstnumber = ( int ) substr ( $card_number, 0, 1 );
	if ($firstnumber === 3) {
		if (! preg_match ( "/^\d{4}$/", $cvv )) {
			// The credit card is an American Express card but does not have a 
      // four digit CVV code
			return false;
		}
	} else if (! preg_match ( "/^\d{3}$/", $cvv )) {
		// The credit card is a Visa, MasterCard, or Discover Card card but does 
    // not have a three digit CVV code
		return false;
	}
	return true;
}

function _validate_expiration_date($card_expiration) {
	return preg_match ( '/^\d{2}\/\d{4}$/', $card_expiration );
}