<!-- Collection of code snippets by Arne Vajhøj -->
<!-- posted to eksperten.dk, usenet and other places (2002-now) -->
<?php
function months($s) {
    $t1 = localtime(strtotime($s), true);
    $t2 = localtime(time(), true);
    return ($t2['tm_year'] - $t1['tm_year']) * 12 + ($t2['tm_mon'] - $t1['tm_mon']) + (($t2['tm_mday'] >= $t1['tm_mday']) ? 0 : -1);
}

echo months('29-Dec-2008') . "\r\n";
echo months('30-Dec-2008') . "\r\n";
echo months('31-Dec-2008') . "\r\n";

?>