Get total number of weekdays in a particular year.

get_total_weekday_in_year.php

<?php

/**
 * Get total number of weekdays in a year.
 *
 * @param  string $day  Week day. Sun, Mon, Tue,...
 * @param  string $year Year in 4 digits.
 * @return integer      Return total number of specified weekday for a year.
 */
function get_total_weekday_in_year( $day = '', $year = '' ) {

	// Bail, if anything goes wrong.
	if ( empty( $day ) ) {
		return;
	}

	// Set current year.
	if ( empty( $year ) ) {
		$year = date( 'Y' );
	}

	$fromdt = date( 'Y-m-01 ', strtotime( "First Day Of  January $year" ) );
	$todt   = date( 'Y-m-31 ', strtotime( "Last Day of December $year" ) );
	$iter   = DAY_IN_SECONDS; // whole day in seconds
	$count  = 0; // keep a count of Weekday

	for ( $i = strtotime( $fromdt ); $i <= strtotime( $todt ); $i = $i + $iter ) {
		if ( Date( 'D', $i ) == $day ) {
			$count++;
		}
	}

	return $count;
}