wp_checkdate( int $month, int $day, int $year, string $source_date )

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

Parameters

$month

(int) (Required) Month number.

$day

(int) (Required) Day number.

$year

(int) (Required) Year number.

$source_date

(string) (Required) The date to filter.

Return

(bool) True if valid date, false if not valid date.

Source

File: 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 );
}

Uses

Uses Description
wp-includes/functions.php: wp_checkdate

Filters whether the given date is valid for the Gregorian calendar.
wp-includes/plugin.php: apply_filters()

Calls the callback functions that have been added to a filter hook.

Used By

Used By Description
wp-includes/post.php: wp_resolve_post_date()

Uses wp_checkdate to return a valid Gregorian-calendar value for post_date.
wp-includes/ms-site.php: wp_validate_site_data()

Validates data for a site prior to inserting or updating in the database.
wp-includes/class-wp-date-query.php: WP_Date_Query::validate_date_values()

Validates the given date_query values and triggers errors if something is not valid.
wp-admin/includes/post.php: _wp_translate_postdata()

Rename $_POST data from form names to DB post columns.
wp-includes/class-wp-customize-manager.php: WP_Customize_Manager::save()

Handle customize_save WP Ajax request to save/update a changeset.
wp-includes/class-wp-query.php: WP_Query::parse_query()

Parse a query string and set query type booleans.
wp-includes/canonical.php: redirect_canonical()

Redirects incoming links to the proper URL based on the site url.

Changelog

Version Description
3.5.0 Introduced.

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Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/functions/wp_checkdate