How do I get the actual category in string ?

My b2evolution Version: 2.x

I need to get the category from Item to eventually compare it then show some banner images if it's the right category...

but i'm totally noob in php

Could someone help having the category in string without using
Item->category() cause it automatically display the result?

$theCategory = get_the_category_by_ID( $Item->main_cat_ID );

with this solution the value of $theCategory always is "array"

but
$theCategory=($Item->main_cat_ID);
is what I was looking for...

so thxs a lot for your FAST help!

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