PHP function to count how many times given day is occurring in then given month, on given date.

count_occurances.php

<?php
/**
* Copyright (C) 2016 Prabhas Gupte
* 
* This is free script: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* 
* This script is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
* 
* You should also see <http://www.gnu.org/licenses/gpl.txt>
*/

function count_occurances($day, $date, $month = 'this month') {
  $first_occurance = date("d", strtotime("first $day of $month"));
  $count = ceil(($date - $first_occurance)/7 + 1);
  return $count; 
}

$day = date("D");
$date_today = date("d");
echo "\nMonday, 20th May: ", count_occurances("Mon", 20);
echo "\n$day, $date_today: ", count_occurances($day, $date_today);
echo "\nMonday, 10th June: ", count_occurances("Mon", 10, 'June 2013');
?>