validating credit card numbers

[delstrange]

Does anyone know of a way to check credit card types and validate the number provided? Say if the user selects 'Discover' for the cc type, check to make sure the acct number is valid and display an error telling them the account number is not a valid "Discover Card Account Number" or to that the card has expired.

Thanks.

[Arc]

Most people outsource this to other companies. It's a pretty complex task, but it can be done. I don't know exactly how though.. goood luck!😃

[nemonoman]

it's not that hard to find the algorighthms:: I found some code and modified it as below.

There's also some javascript that can do this on the front end, before the user submits the form. see:
http://javascript.internet.com/forms/val-credit-card.html

function CardCheck($ccnum, $cctype = '') {
if (!isset($ccnum)) return FALSE;
// Make credit card number purely numeric
$ccnum = ereg_replace('[^{[:digit:]]+',} '', $ccnum);
// Validate digit length for Visa
if (ereg('^4', $ccnum)) {
$cctype = "VISA";
if (strlen($ccnum) <> 13 && strlen($ccnum) <> 16) return FALSE;
}
// Validate digit length for MasterCard
if (ereg('^5[1-5]', $ccnum)) {
$cctype = "MAST";
if (strlen($ccnum) <> 16) return FALSE;
}
// Validate digit length for American Express
if (ereg('^3[47]', $ccnum)) {
$cctype = "AMEX";
if (strlen($ccnum) <> 15) return FALSE;
}
// Validate digit length for Discover/Novus
if (ereg('^6011', $ccnum)) {
$cctype = "DISC";
if (strlen($ccnum) <> 16) return FALSE;
}
// Perform LUHN (mod10) test on card number
$sum = 0;
$len = strlen($ccnum);
// Double every other digit from right to left
$mask = substr("2121212121212121", 16-$len, $len);
// Now iterate and operate on credit card digits
for($idx = 0; $idx < $len; $idx++) {
$digit = substr($ccnum, $idx, 1);
$mult = substr($mask, $idx, 1);
if ($mult == "2") {
$sum += ($digit >= 5) ? 1+(($digit 2)%10) :
$digit 2;
} else {
$sum += $digit;
}
}
if ($sum%10) return FALSE;
// No mod10 remainder, card sequence is valid!
return TRUE;
}

[superwormy]

To validate credit card NUMBERS, you need Luhn Formula:
http://www.google.com/search?sourceid=navclient&ie=UTF-8&oe=UTF-8&q=luhn+formula

NOTE THAT THIS DOES NOT VALIDATE DATES!

The only way to check if the card is ACTUALLY VALID is to run the card with a CC machine / over the internet to whoever your merchent account / CC charging person is.

[delstrange]

Thanks everyone, I'll give them a shot.

[delstrange]

nemonoman, I need help with this. All I know about PHP is what I have learned from this forum.

Anyway, how do I use the script you just gave above?

I tried doing this:

<?php
//form.php
function CardCheck($ccNum, $ccType = '') {
if (!isset($ccNum)) return FALSE;
// Make credit card number purely numeric
$ccnum = ereg_replace('[^{[:digit:]]+',} '', $ccNum);
// Validate digit length for Visa
if (ereg('^4', $ccNum)) {
$ccType = "V";
if (strlen($ccNum) <> 13 && strlen($ccNum) <> 16) return FALSE;
}

.......then the rest of the code. Plus underneath this I have error checking for empty fields that are required.

The form action is: action=<? $PHP_SELF ?>

But the credit card validation is a function. So how do I tell it to run the CardCheck function and the $PHP_SELF at the same time? Or what do I need to put as the action for the form?

I have attached a .txt file of all the code and the way I have it set up. Of course I know it is wrong because it isn't working.

Can you help?

Thanks.

[Weedpacket]

You have the CardCheck() function in the page with the form, so the action is PHP_SELF.

When the form submits, it submits to itself.

So at the start of the form, you look to see if there is any form data to process (specifically, $POST['ccNum'] and $POST['ccType']). If there is, call

$check = CardCheck($_POST['ccNum'], $_POST['ccType']);

And then look to see if($check) is true or false. If true, then the number validated; if false, it didn't.

[delstrange]

okay, I guess I still don't quite get it. Could you do me a huge favor and edit the .txt file attached from my last post and send it back to me the way it should look?

Thanks.