WP get_the_category() only returns 1 category or not returning (problem solved)

Category: Problems with code/cms and solution, WordPress

An example of old code that didn’t work well:

$category = get_the_category();
echo $category[0]->name;

An example of a correctly working code:

$cats = wp_get_post_categories( $post->ID, [ 'fields' => 'all' ] );
    foreach( $cats as $cat ){
        echo $cat->name;
    }

An example code for the case when you need to display subcategories other than the main one:

$cats = wp_get_post_categories( $post->ID, [ 'fields' => 'all' ] );
    foreach( $cats as $cat ){
        if ( ( $cat->term_id !== 1 ) && ( $cat->term_id !== 2 ) && ( $cat->term_id !== 3 ) )
        echo $cat->name;
        // echo $cat->term_id;
    }

Covert testing code:

<?php
if ( $ip != '00.00.00.00 ') {

} else {

}   
?>