Name from User ID

// Add Shortcode
function Name_from_ID( $atts , $content = null ) {

	// Code
$u_name = get_user_meta( $content, 'first_name', $single=true ) . ' ' .get_user_meta( $content, 'last_name', $single=true ) ;
return $u_name;
}
add_shortcode( 'nfid', 'Name_from_ID' );