Our CCreditCard class is flexible: it accepts several different ways to specify the type of card that is being stored. It is special in the sense that it is automatically executed whenever we create a new instance of that class. A constructor is a function that has the same names as the class in which it exists. Next we have our class’ custom constructor. We also define five member variables, which will be used internally to hold the credit card’s name, type, number, expiry month and year: class CCreditCard Note that there is an extra ‘C’ at the front of the class name intentionally: it’s a common programming practice to prefix the name of a class with ‘C’ to in fact indicate that it is a class. These values will be used to represent the type of card that our class will be validating:
#Algorthm for a credit card validator code
As we walk through the following steps, copy-paste each piece of code shown to the file and save it. Our class will be able to hold the cardholder’s name, the card type (mastercard, visa, etc), the card number, and the expiry month and date.Ĭreate a new PHP file called. Let’s now create a PHP class that we can use to store and validate the details of a credit card.
#Algorthm for a credit card validator mod
Now that we understand the Mod 10 algorithm, it’s really quite easy to create our own version to validate credit card numbers with PHP. The modulus operation returns 0, indicating that the credit card number is valid. So for our test credit card number 378282246310005, we apply a modulus of 10 to the result from step two, like this: The modulus operator simply returns the remainder of a division, for example:ġ0 MOD 5 = 0 (5 goes into 10 two times and has a remainder of 0)Ģ0 MOD 6 = 2 (6 goes into 20 three times and has a remainder of 2)Ĥ3 MOD 4 = 3 (4 goes into 43 ten times and has a remainder of 3) When a modulus operation is applied to the result of step two, the remainder must equal 0 in order for the number to pass the Mod 10 algorithm. The number is reversed and the value of every second digit is doubled, starting with the digit in second place:Īnd the value of every second digit is doubled: We will use the valid credit card number 378282246310005 to demonstrate these steps:
There are three steps that the Mod 10 algorithm takes to determine whether or not a credit card number is valid. Before we create that class however, let’s look at how the Mod 10 algorithm works. whether it passed the Mod 10 algorithm or not). JCB: Must have a prefix of 3, 1800, or 2131, and must be either 15 or 16 digits in length.Īs mentioned earlier, in this article we will create a PHP class that will hold the details of a credit card number and expose a function that indicates whether or not the number of that credit card is valid (i.e.Discover: Must have a prefix of 6011, and must be 16 digits in length.Diners Club: Must have a prefix of 300 to 305, 36, or 38, and must be 14 digits in length.
American Express: Must have a prefix of 34 or 37, and must be 15 digits in length.Visa: Must have a prefix of 4, and must be either 13 or 16 digits in length.mastercard: Must have a prefix of 51 to 55, and must be 16 digits in length.A list of these rules for each of the six most popular credit cards is shown below: There are several different types of credit cards that one can use to make a purchase, however they can all be validated using the Mod 10 algorithm.Īs well as passing the Mod 10 algorithm, a credit card number must also pass several different formatting rules. This algorithm processes some simple numerical data validation routines against the number, and the result of this algorithm can be used to determine whether or not a credit card number is valid. What do we actually mean when we say "validate a credit card number"? Quite simply it means that we run a credit card number through a special algorithm known as the Mod 10 algorithm. To implement the class we’ll create in this article, you should have access to an Apache web server running PHP 4.1.0 or later. In this article we’re going to work through the development of a PHP class that stores the details of a credit card and validates its number using the Mod 10 algorithm. Before you actually encrypt your customer’s credit card numbers to a database or forward them to a merchant server, it’s a good idea to implement your own credit card validation routine. Although online payment options such as PayPal have become extremely popular in the last couple of years, the majority of online stores still use some sort of merchant system to accept credit card payments from their Websites.
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