Re: checking of credit card num.

-- John <john@edlabs.com> wrote: > hi, > is there any way i can validate the credit card num? Hi John, The function below returns the type of the credit card, based on the number. If it's an invalid number it returns false. This version only does Visa, Mastercard and American Express, but it's easy to add in any other cards that you accept. HTH, Colin function GetCardType($ccnum) { // initialize variables $sum = 0; $mul = 1; $l = strlen($ccnum); // calculate checksum for ( $i=0; $i<$l; $i++) { $digit = $ccnum[$l-$i-1]; $tproduct = $digit * $mul; if ($tproduct >= 10) $sum += ($tproduct % 10) + 1; else $sum += $tproduct; if ($mul == 1) $mul++; else $mul--; } // screen checksum if (($sum % 10) != 0) return false; // check for Visa if ( (($l==16) || ($l==13)) && ($ccnum[0]==4) ) return "VI"; // check for Master Card if ( ($l==16) && ($ccnum[1]==5) && ($ccnum[1]>=1) && ($ccnum[1]<=5) ) return "CA"; // check for Amex if ( ($l==15) && ($ccnum[0]==3) && (($ccnum[1]==4) || ($ccnum[1]==7)) ) return "AX"; // if we got this far, then no card matched return false; } --------------------------------------------- Colin Putney cputney@whistler.net Whistler Networks http://www.whistler.net/