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credit card validation

westminster86

By westminster86
in PHP Coding Help

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westminster86 Member

westminster86

Posted
Posted

Ive echoed out the two form fields and it doesnt seem to be posting the two form variables, and so is not calling the function.

<html>
<head>
</head>
<body>
<table border = 0 width = '100%' cellspacing = 0>
  <form action = '' method = 'post'>
  <tr><th colspan = 2 bgcolor="#cccccc">Credit Card Details</th></tr>
<tr>
    <td>Card Type:</td>
    <td><select name = 'CardType'><option><option>American Express<option>Maestro<option>MasterCard<option>Solo<option>Switch<option>Visa<option>Visa Electron</select></td>
  </tr>
<tr>
    <td>Number:</td>
    <td><input type = 'text' name = 'CardNumber' value = "" maxlength = 19 size = 20></td>
  </tr>
<tr>
  <td><input type='submit' name='submit' value='submit'></td>
</tr>
</form>
</table>

</body>
</html>

<?php

if (isset($_POST['submit'])) {
  if (checkCreditCard ($_POST['CardNumber'], $_POST['CardType'], $ccerror, $ccerrortext)) {
    $ccerrortext = 'This card has a valid format';
  }
}


function checkCreditCard ($cardnumber, $cardname, &$errornumber, &$errortext) {

  $cards = array (  array ('name' => 'American Express', 
                          'length' => '15', 
                          'prefixes' => '34,37',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Maestro', 
                          'length' => '16,18', 
                          'prefixes' => '5020,6',
                          'checkdigit' => true
                         ),
                   array ('name' => 'MasterCard', 
                          'length' => '16', 
                          'prefixes' => '51,52,53,54,55',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Solo', 
                          'length' => '16,18,19', 
                          'prefixes' => '6334,6767',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Switch', 
                          'length' => '16,18,19', 
                          'prefixes' => '4903,4905,4911,4936,564182,633110,6333,6759',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Visa', 
                          'length' => '13,16', 
                          'prefixes' => '4',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Visa Electron', 
                          'length' => '16', 
                          'prefixes' => '417500,4917,4913',
                          'checkdigit' => true
                         )
                );

  $ccErrorNo = 0;

  $ccErrors [0] = "Unknown card type";
  $ccErrors [1] = "No card number provided";
  $ccErrors [2] = "Credit card number has invalid format";
  $ccErrors [3] = "Credit card number is invalid";
  $ccErrors [4] = "Credit card number is wrong length";
               
  // Establish card type
  $cardType = -1;
  for ($i=0; $i<sizeof($cards); $i++) {

    // See if it is this card (ignoring the case of the string)
    if (strtolower($cardname) == strtolower($cards[$i]['name'])) {
      $cardType = $i;
      break;
    }
  }
  
  // If card type not found, report an error
  if ($cardType == -1) {
     $errornumber = 0;     
     $errortext = $ccErrors [$errornumber];
     return false; 
  }
   
  // Ensure that the user has provided a credit card number
  if (strlen($cardnumber) == 0)  {
     $errornumber = 1;     
     $errortext = $ccErrors [$errornumber];
     return false; 
  }
  
  // Remove any spaces from the credit card number
  $cardNo = str_replace (' ', '', $cardnumber);  
   
  // Check that the number is numeric and of the right sort of length.
  if (!eregi('^[0-9]{13,19}$',$cardNo))  {
     $errornumber = 2;     
     $errortext = $ccErrors [$errornumber];
     return false; 
  }
       
  // Now check the modulus 10 check digit - if required
  if ($cards[$cardType]['checkdigit']) {
    $checksum = 0;                                  // running checksum total
    $mychar = "";                                   // next char to process
    $j = 1;                                         // takes value of 1 or 2
  
    // Process each digit one by one starting at the right
    for ($i = strlen($cardNo) - 1; $i >= 0; $i--) {
    
      // Extract the next digit and multiply by 1 or 2 on alternative digits.      
      $calc = $cardNo{$i} * $j;
    
      // If the result is in two digits add 1 to the checksum total
      if ($calc > 9) {
        $checksum = $checksum + 1;
        $calc = $calc - 10;
      }
    
      // Add the units element to the checksum total
      $checksum = $checksum + $calc;
    
      // Switch the value of j
      if ($j ==1) {$j = 2;} else {$j = 1;};
    } 
  
    // All done - if checksum is divisible by 10, it is a valid modulus 10.
    // If not, report an error.
    if ($checksum % 10 != 0) {
     $errornumber = 3;     
     $errortext = $ccErrors [$errornumber];
     return false; 
    }
  }  

  // The following are the card-specific checks we undertake.

  // Load an array with the valid prefixes for this card
  $prefix = split(',',$cards[$cardType]['prefixes']);
      
  // Now see if any of them match what we have in the card number  
  $PrefixValid = false; 
  for ($i=0; $i<sizeof($prefix); $i++) {
    $exp = '^' . $prefix[$i];
    if (ereg($exp,$cardNo)) {
      $PrefixValid = true;
      break;
    }
  }
      
  // If it isn't a valid prefix there's no point at looking at the length
  if (!$PrefixValid) {
     $errornumber = 3;     
     $errortext = $ccErrors [$errornumber];
     return false; 
  }
    
  // See if the length is valid for this card
  $LengthValid = false;
  $lengths = split(',',$cards[$cardType]['length']);
  for ($j=0; $j<sizeof($lengths); $j++) {
    if (strlen($cardNo) == $lengths[$j]) {
      $LengthValid = true;
      break;
    }
  }
  
  // See if all is OK by seeing if the length was valid. 
  if (!$LengthValid) {
     $errornumber = 4;     
     $errortext = $ccErrors [$errornumber];
     return false; 
  };   
  
  // The credit card is in the required format.
  return true;
}

?>

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