HTML dropdown setting not showing last saved value in the database

Question

I want a select-dropdown field to display the last saved option in the database; I started with this video from YT, https://www.youtube.com/watch?v=hbJiwm5YL5Q&t=3969s and got as far as 1:05:00 and this is my current version

function selectpageHTML() {?>
            <select name="lp_actPage"> 
                <?  $pages = get_pages();
                        foreach ( $pages as $page ) {                               
                                $slug = $page->post_name;
                                $title = $page->post_title;
                                echo "<option value='$slug'" . selected(get_option('lp_actPage', $slug)) .">$title</option>";
                        } ?>
            </select>
        <?} 

I also looked at Select dropdown not showing selected value php, but instead of comparing floats I'm looking to compare strings.

Answer 1

The problem is this:

selected(get_option('lp_actPage', $slug))

selected needs 2 parameters, but you gave it 1, and get_option wants 1 parameter but you gave it 2.

If we reformat this, the problem becomes much clearer:

selected(
    get_option('lp_actPage', $slug)
)

What's necessary is:

selected(
    get_option('lp_actPage')
    $slug
)

Sidenote

get_pages doesn't use the normal post querying code, and doesn't benefit from the same enhancements and plugin integration you get from other functions.

Instead of get_pages, consider:

$pages = get_posts( [
    'suppress_filters' => false, // enable caching
    'post_type' => 'page', // we want pages
    'post_status' => 'publish', // speed up by asking for only published posts
    'posts_per_page' => 100,
] );

Likewise, don't use <? use <?php or your code will break when your host upgrades PHP in the future.