CFLib.org – Common Function Library Project

Description:
Returns TRUE if the given credit card number is well-formed according to the industry-standard Luhn algorithm, and (optionally) conforms with basic formatting rules applicable to the specific card type, e.g. Visa, Mastercard. <strong> CAUTION: Note that this does not prove that the card has not been revoked, stolen etc.</strong> Non-numeric characters in the card number string are simply ignored.

Return Values:
Returns a boolean.

Example:

<CFOUTPUT>
Is the card number 5418590012345679 valid? #IsCreditCard("5418590012345679")#
<P>
Is the card number 5418590012345679 a valid Mastercard? #IsCreditCard("5418590012345679", "MASTERCARD")#
<P>
Is 541A590012345679 valid? #IsCreditCard("541A590012345679")#
<P>
Is the card number 541 8590 01234 5679 valid? #IsCreditCard("541 8590 01234 5679")#

</cfoutput>

Parameters:

Full UDF Source:

/**
 * Returns TRUE if the string is a valid credit card number.
 * Modded by RCamden - Check for any non numeric and return false.
 * Modded by Author - fixed mastercard checking
 * Updated to use [:digit:] and allow spaces
 * Corrected nondigit check
 * 
 * @param ccNo      The credit card number. (Required)
 * @param cardType      One of: AMEX, DINERS, DISCOVER, MASTERCARD, VISA (Optional)
 * @return Returns a boolean. 
 * @author Nick de Voil (nick@devoil.com) 
 * @version 4, August 17, 2004 
 */
function IsCreditCard(ccNo)
{
    var rv = "";
    var str = "";
    var chk = 0;
    var ccln = 0;
    var strln = 0;
    var i = 1;

    if(reFind("[^[:digit:]]",ccNo)) return FALSE;
        ccNo = replace(ccNo," ","","ALL");
    rv = Reverse(ccNo);
    ccln = Len(ccNo);
    if(ccln lt 12) return FALSE;
    for(i = 1; i lte ccln;  i = i + 1) {
        if(i mod 2 eq 0) {
            str = str & Mid(rv, i, 1) * 2;
        } else {
            str = str & Mid(rv, i, 1);
        }
    }
    strln = Len(str);
    for(i = 1; i lte strln; i = i + 1) chk = chk + Mid(str, i, 1);
    if((chk neq 0) and (chk mod 10 eq 0)) {
        if(ArrayLen(Arguments) lt 2) return TRUE;
        switch(UCase(Arguments[2])) {
        case "AMEX":        if ((ccln eq 15) and (((Left(ccNo, 2) is "34")) or ((Left(ccNo, 2) is "37")))) return TRUE; break;
        case "DINERS":        if ((ccln eq 14) and (((Left(ccNo, 3) gte 300) and (Left(ccNo, 3) lte 305)) or (Left(ccNo, 2) is "36") or (Left(ccNo, 2) is "38"))) return TRUE; break;
        case "DISCOVER":    if ((ccln eq 16) and (Left(ccNo, 4) is "6011")) return TRUE; break;
        case "MASTERCARD":    if ((ccln eq 16) and (Left(ccNo, 2) gte 51) and (Left(ccNo, 2) lte 55)) return TRUE; break;
        case "VISA":        if (((ccln eq 13) or (ccln eq 16)) and (Left(ccNo, 1) is "4")) return TRUE; break;
        default: return TRUE;
        }
    }
    return FALSE;
}