Welcome to our PHP lesson on implementing a data structure with unique elements using associative arrays! In PHP, associative arrays can be leveraged to create collections that store unique elements efficiently by using keys to represent the elements. While PHP does not have a native set type, associative arrays provide a flexible and powerful way to achieve the same functionality, allowing us to ensure that elements are unique within our collections. In many other programming languages, this data structure is referred to as a HashSet.

In this lesson, you'll learn how to create and manipulate this unique-element data structure using PHP associative arrays, gaining insights into operations typically performed, such as union, intersection, and difference. Let's begin!

Let's start by creating a data structure with unique elements in PHP using an associative array. The unique keys in the associative array allow us to store elements uniquely.

In this example, we use the uniqueness of array keys to create this data structure. By checking the existence of keys using isset, we determine whether an element is present. We clear the structure by reinitializing it as an empty array.