Personal Greeting Shortcode

Below is the copy-and-paste code snippet as mentioned in the above video:

/*
 This shortcode [get-user-first-name] will display the logged in Users first name only. 
 */
add_shortcode('get-user-first-name','get_user_first_name');
function get_user_first_name()
{
	$current_user 	= wp_get_current_user();
	$first_name 	= $current_user->user_firstname;
	$last_name 	= $current_user->user_lastname ;
	return $first_name;
}

/*
 This shortcode [greet_user] will display the word Welcome followed by the logged in Users first name. 
 */

add_shortcode('greet_user','greet_user');
function greet_user()
{
	$current_user 	= wp_get_current_user();
	$first_name 	= $current_user->user_firstname;
	$last_name 	= $current_user->user_lastname ;
	return "Welcome, $first_name";
}