- date: documentation ( source)
- strtotime: documentation ( source)
<?php
$dt = new DateTime('first Monday of this month');
echo $dt->format('W');
$month = "3";
$year = "2014";
$beg = (int) date('W', strtotime("first monday of $year-$month"));
$end = (int) date('W', strtotime("last monday of $year-$month"));
for($i = $beg; $i <= $end; ++$i) { print $i; }