Examine a url and try to determine the post ID it represents.

Checks are supposedly from the hosted site blog.

Signature

url_to_postid( $url )
url
 (string) Permalink to check.

Return

(int) Post ID, or 0 on failure.

Source

function url_to_postid($url) {
	global $wp_rewrite;

	/**
	 * Filter the URL to derive the post ID from.
	 *
	 * @since 2.2.0
	 *
	 * @param string $url The URL to derive the post ID from.
	 */
	$url = apply_filters( 'url_to_postid', $url );

	// First, check to see if there is a 'p=N' or 'page_id=N' to match against
	if ( preg_match('#[?&](p|page_id|attachment_id)=(\d+)#', $url, $values) )	{
		$id = absint($values[2]);
		if ( $id )
			return $id;
	}

	// Check to see if we are using rewrite rules
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