Add last updated date to posts

I tried adding this to functions.php but didn't work;

function wpb_last_updated_date( $content ) {
$u_time = get_the_time('U');
$u_modified_time = get_the_modified_time('U');
if ($u_modified_time >= $u_time + 86400) {
$updated_date = get_the_modified_time('F jS, Y');
$updated_time = get_the_modified_time('h:i a');
$custom_content .= '<p class="last-updated">Last updated on '. $updated_date . ' at '. $updated_time .'</p>';
}

$custom_content .= $content;
return $custom_content;
}
add_filter( 'the_content', 'wpb_last_updated_date' );

Hi there,

do you want to display both Published and Updated dates ?

If so the easiest method is to create your own post meta template:

https://docs.generatepress.com/article/block-element-post-meta-template/

Thanks for the reply.
I'd prefer just the updated date if it's not a hassle?

I noticed there's a plugin for php but is that wise to use?

Hi Robert,

The CSS should work, can you link us to your post which has been updated?

sure; https://www.watercolorfanatic.com/how-to-paint-a-watercolor-landscape-step-by-step-video-tutorial/

Add the first CSS from the below article as well:
https://docs.generatepress.com/article/show-the-updated-post-date/

That worked!
So, just to confirm using the functions.php file isn't recommended? Doesn't work?
Does css degrade site speed over time if too much is used?
Thanks

So, just to confirm using the functions.php file isn’t recommended? Doesn’t work?

It's not needed. As the updated date and post date are both already in the HTML.

Does css degrade site speed over time if too much is used?

Yes, if we are talking about hundreds and thousands lines of CSS.

You are welcome :)

thanks again for the help

No problem :)