wpseek.com
A WordPress-centric search engine for devs and theme authors

function count_user_posts( $userid, $post_type = 'post', $public_only = false ) {
	global $wpdb;

	$post_type = array_unique( (array) $post_type );
	sort( $post_type );

	$where = get_posts_by_author_sql( $post_type, true, $userid, $public_only );
	$query = "SELECT COUNT(*) FROM $wpdb->posts $where";

	$last_changed = wp_cache_get_last_changed( 'posts' );
	$cache_key    = 'count_user_posts:' . md5( $query ) . ':' . $last_changed;
	$count        = wp_cache_get( $cache_key, 'post-queries' );
	if ( false === $count ) {
		$count = $wpdb->get_var( $query );
		wp_cache_set( $cache_key, $count, 'post-queries' );
	}

	/**
	 * Filters the number of posts a user has written.
	 *
	 * @since 2.7.0
	 * @since 4.1.0 Added `$post_type` argument.
	 * @since 4.3.1 Added `$public_only` argument.
	 *
	 * @param int          $count       The user's post count.
	 * @param int          $userid      User ID.
	 * @param string|array $post_type   Single post type or array of post types to count the number of posts for.
	 * @param bool         $public_only Whether to limit counted posts to public posts.
	 */
	return apply_filters( 'get_usernumposts', $count, $userid, $post_type, $public_only );
}