<?php
function abavalidate($aba)
{
// First, check for 9 digits and non-numeric characters.
if (ereg("^[0-9]{9}$",$aba))
{
$n = 0;
for ($i = 0; $i < 9; $i += 3)
{
$n += (substr($aba,$i,1) * 3)
+ (substr($aba,$i + 1,1) * 7)
+ (substr($aba,$i + 2,1));
}...