wp_checkdate() │ WP 3.5.0

Test if the supplied date is valid for the Gregorian calendar.

1 time — 0.00002 sec (very fast) | 50000 times — 0.10 sec (speed of light)
Hooks from the function

Return

true|false. True if valid date, false if not valid date.

Usage

wp_checkdate( $month, $day, $year, $source_date );
$month(int) (required)
Month number.
$day(int) (required)
Day number.
$year(int) (required)
Year number.
$source_date(string) (required)
The date to filter.

Examples

0

#1 An example from the WordPress core 

/*
 * If the date is not set ( new post or draft)
 * if it is not a draft or the date was changed in the process of writing.
 */
if ( empty( $postarr['post_date'] ) || '0000-00-00 00:00:00' == $postarr['post_date'] ) {
	$post_date = current_time( 'mysql' );
}
else {
	$post_date = $postarr['post_date'];
}

// Date Validation.
$mm = substr( $post_date, 5, 2 );
$jj = substr( $post_date, 8, 2 );
$aa = substr( $post_date, 0, 4 );
$valid_date = wp_checkdate( $mm, $jj, $aa, $post_date );

if ( ! $valid_date ) {
	if ( $wp_error ) {
		//The specified date is incorrect.
		return new WP_Error( 'invalid_date', __( 'Whoops, the provided date is invalid.' ) );
	}
	else {
		return 0;
	}
}
0

#2 Another example from the WordPress core 

if ( get_query_var( 'day' ) && get_query_var( 'monthnum' ) && get_query_var( 'year' ) ) {
	$year  = get_query_var( 'year' );
	$month = get_query_var( 'monthnum' );
	$day   = get_query_var( 'day' );
	$date  = sprintf( '%04d-%02d-%02d', $year, $month, $day );
	if ( ! wp_checkdate( $month, $day, $year, $date ) ) {
		$redirect_url = get_month_link( $year, $month );
	}
}

Changelog

Since 3.5.0 Introduced.

wp_checkdate() code WP 6.1.1

wp-includes/functions.php 
function wp_checkdate( $month, $day, $year, $source_date ) {
	/**
	 * Filters whether the given date is valid for the Gregorian calendar.
	 *
	 * @since 3.5.0
	 *
	 * @param bool   $checkdate   Whether the given date is valid.
	 * @param string $source_date Date to check.
	 */
	return apply_filters( 'wp_checkdate', checkdate( $month, $day, $year ), $source_date );
}

date time