CFLib.org – Common Function Library Project

Description:
Given the first 11 digits of a UPC-A barcode, returns the 12th check digit.

Return Values:
Returns a numeric value.

Example:

<cfset barcode=12345678901>
<cfoutput>
Check digit for #barcode# is #UPCCheckDigit(barcode)#
</cfoutput>

Parameters:

Full UDF Source:

/**
 * Calculates a UPC-A check digit.
 * 
 * @param upc      11 digit UPC-A code (Required)
 * @return Returns a numeric value. 
 * @author Pete Jacoby (cf@subnova.net) 
 * @version 1, June 15, 2002 
 */
function UPCCheckDigit(upc){
var odd = 0;
var even = 0;
var total = 0;

if (NOT IsNumeric(upc) OR Len(upc) NEQ 11)
    return(-1);

for (i=1; i LT 12; i=i+1){
        if (i MOD 2)
            odd=odd+Mid(upc, i, 1);
        else
            even=even+Mid(upc, i, 1);
    }

total=(odd*3)+even;
total=total mod 10;

if (total eq 0)
    return 0;
else
    return(10-total);
}