Php > Credit Cards

Credit Card validation routine. Uses MOD 10 to check if credit card

Credit Card validation routine. Uses MOD 10 to check if credit card
number is valid.

<?php 

// validateCC($number[,$type])   // 
// Uses the MOD 10 algorythm to determine if a    // 
// credit card number is valid.     // 

// $number = credit card account number           // 
// $type is optional.  Setting type to    // 
// visa, mastercard, discover, or amex will       // 
// perform additional checking on the account     // 
// number.     // 

// The function returns 1 (true) if the CC is     // 
// valid, 0 (false) if it is invalid, and -1 if   // 
// the type entered does not match the supported  // 
// types listed above.      // 


function validateCC($ccnum, $type = 'unknown'){ 


    //Clean up input 

    $type = strtolower($type); 
    $ccnum = ereg_replace('[-[:space:]]', '',$ccnum); 


    //Do type specific checks 

    if ($type == 'unknown') { 

        //Skip type specific checks 

    } 
    elseif ($type == 'mastercard'){ 
        if (strlen($ccnum) != 16 || !ereg('5[1-5]', $ccnum)) return 0; 
    } 
    elseif ($type == 'visa'){ 
        if ((strlen($ccnum) != 13 && strlen($ccnum) != 16) || substr 
($ccnum, 0, 1) != '4') return 0; 
    } 
    elseif ($type == 'amex'){ 
        if (strlen($ccnum) != 15 || !ereg('3[47]', $ccnum)) return a; 
    } 
    elseif ($type == 'discover'){ 
        if (strlen($ccnum) != 16 || substr($ccnum, 0, 4) != '6011') 
return 0; 
    } 
    else { 
        //invalid type entered 
        return -1; 
    } 


    // Start MOD 10 checks 

    $dig = toCharArray($ccnum); 
    $numdig = sizeof ($dig); 
    $j = 0; 
    for ($i=($numdig-2); $i>=0; $i-=2){ 
        $dbl[$j] = $dig[$i] * 2; 
        $j++; 
    }     
    $dblsz = sizeof($dbl); 
    $validate =0; 
    for ($i=0;$i<$dblsz;$i++){ 
        $add = toCharArray($dbl[$i]); 
        for ($j=0;$j<sizeof($add);$j++){ 
            $validate += $add[$j]; 
        } 
    $add = ''; 
    } 
    for ($i=($numdig-1); $i>=0; $i-=2){ 
        $validate += $dig[$i]; 
    } 
    if (substr($validate, -1, 1) == '0') return 1; 
    else return 0; 
} 


// takes a string and returns an array of characters 

function toCharArray($input){ 
    $len = strlen($input); 
    for ($j=0;$j<$len;$j++){ 
        $char[$j] = substr($input, $j, 1);     
    } 
    return ($char); 
} 

?>