WordPress at a glance
function is not described

WP_Query::is_404() WP 3.1.0

Is the query a 404 (returns no results)?

This is a method of the class: WP_Query

No Hooks.

Return

true/false.

Usage

$WP_Query = new WP_Query();
$var = $WP_Query->is_404();

Changelog

Since 3.1.0 Introduced.

Code of WP Query::is 404: wp-includes/class-wp-query.php WP 5.2.3

<?php
public function is_404() {
	return (bool) $this->is_404;
}