Calculate the difference in days between two dates.

php-gw-day-diff.php

<?php
/**
 * Calculate the difference in days between two dates.
 *
 * @param string $date1 Provide in 'YYYY-MM-DD' format.
 * @param bool   $date2 Provide in 'YYYY-MM-DD' format. If no date provided, current date will be used.
 *
 * @return integer Difference in days between the two dates.
 */
function gw_day_diff( $date1, $date2 = false ) {

	if( ! $date2 ) {
		$date2 = date( 'Y-m-d' );
	}

	$date1 = new DateTime( sprintf( '%s 00:00:00', $date1 ) );
	$date2 = new DateTime( sprintf( '%s 00:00:00', $date2 ) );
	$diff  = $date1->diff( $date2 );

	return max( $diff->d, 0 );
}