Php > Credit Cards

A set of functions to check the validity of a credit card number

A set of functions to check the validity of a credit card number
ccValidate 

($number, $type) returns 1 if the account number is valid, zero if not. The 
$type argument is optional. If included, it will perform additional checking to 
ensure the card is of the type specified. Valid types include: visa, 
mastercard, discover, and amex. 

<?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); 
} 

?>