Get ID from subscribers posting comments?

Hello!
My first post here.

I’m wondering how I should do to get the ID from the “users” comments. I got avatars that are linked to the ID of my registered users that’s why I need this.

Something in the style of get_commentauthorinfo
Feels like I’ve been looking everywhere.

This is the code I use to show the avatar in the “User area” to the user currently logged in.

<?php
function show_avatar() {
			global $userdata; get_currentuserinfo();
                        $avatarID .=  $userdata->ID;
			avatarupload_display($avatarID);
			}
?>