Check if a creditcard is valid without sending information to an outside website. AMEX, VISA and MASTERCARD supported.

By : smckone

This script is object orianted but I included a simple wrapper funtion.
It makes it easy by just entering the card number and returning a boolean true or false;

boolean IsCardValid(int);
boolean IsCardValid(string);

<?php
/**************************************************
Credit Card Validation
Check if a creditcard is valid without
sending information to an outside
website. AMEX, VISA and MASTERCARD supported.

Sam McKone <sam@evilwalrus.com>

v1.0 (Dec 5. 2001)
***************************************************/

class CCValidation{
// static variables
var $INVALID = -1;
var $VISA = 1;
var $MASTERCARD = 2;
var $AMEX = 3;
var $CARD_NAMES = array("Visa","Mastercard","American Express");

// data members
var $CardNumber = "";

function CCValidation($set_num){
$this->CardNumber = $set_num;

}
function setCardNumber($set_num){
$this->CardNumber = $set_num;
}
function CheckCardID(){
$valid = $INVALID;

$digits1 = substr($this->CardNumber,0,1);
$digits2 = substr($this->CardNumber,0,2);
$digits4 = substr($this->CardNumber,0,4);

if($digit1 == 4){
if(strlen($this->CardNumber) == 13 || strlen($this->CardNumber) == 16){
$valid = $VISA;
}
}else if($digit2 >= 51 && $digit2 <= 55){
if(strlen($this->CardNumber) == 16){
$valid = $MASTERCARD;
}
}else if($digit2 == 34 || $digit2 == 37){
if(strlen($this->CardNumber) == 15){
$valid = $AMEX;
}
}
return $valid;
}
function CheckCardNumber(){
$cardTemp = $this->CardNumber;
$checkSum = 0;

for($i = (strlen($cardTemp) -1);$i >= 0; $i -= 2){
$j = 0;
if(i > 0){
$j = substr($cardTemp,$i-1,$i) * 2;
if($j > 9){
$s = $j;
$j = substr($s,0,1) + substr($s,1);
}
$checkSum += substr($s,0,1) + $j;
}else{
$checkSum += substr($cardTemp,0,1);
}
}
return (($checkSum % 10) == 0);
}
function CheckCard(){
if($this->CheckCardID() != -1){
return $this->CheckCardNumber();
}
return false;
}
}
function IsCardValid($card_num){
$card = new CCValidation($card_num);
return $card->CheckCard();
}
?>

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