How can you put the two if statements together? If you use OR, doesn't it always display all items? So confused...

At the beginning of each loop irritation, PHP checks if the first condition is true. If it is - PHP trims and sorts the current item (not every item) and never proceeds to the second condition. When looping through the catalog arrays is finished, all the items are shown on the page. However - if the first condition is false (meaning $section is not equal to null), PHP moves to the second condition and checks if it's true. If it is - only the items that match the second conditional statement are being trimmed, sorted and displayed on the page.

The condition $category == null is used to display all items

The condition strtolower($category) == strtolower($item["category"]) is used to display items for a particular category. For example if $category is "Books" then books display but not music or movies so not all items are included. Every item is not true for one of the two. In the example I gave for a catalog item with category "Music", $category of "Books" isn't null but also "books" doesn't equal "music" so both conditions are false.

I have the same question, and I still don't understand. The if statement is doing the same thing for both conditions. Wasn't the whole point to do different things?