add_shortcode( string $tag, callable $callback )

63function add_shortcode( $tag, $callback ) {64	global $shortcode_tags;65 66	if ( '' === trim( $tag ) ) {67		_doing_it_wrong(68			__FUNCTION__,69			__( 'Invalid shortcode name: Empty name given.' ),70			'4.4.0'71		);72		return;73	}74 75	if ( 0 !== preg_match( '@[<>&/\[\]\x00-\x20=]@', $tag ) ) {76		_doing_it_wrong(77			__FUNCTION__,78			sprintf(79				/* translators: 1: Shortcode name, 2: Space-separated list of reserved characters. */80				__( 'Invalid shortcode name: %1$s. Do not use spaces or reserved characters: %2$s' ),81				$tag,82				'& / < > [ ] ='83			),84			'4.4.0'85		);86		return;87	}88 89	$shortcode_tags[ $tag ] = $callback;90}