What is the difference between using an array and using a set in programming?

An array and a set are different data structures with different properties and uses:

• Array — an ordered collection of elements, allowing duplicates. Elements are accessible by index, enabling quick access by position.

• Set — an unordered collection of unique elements. Duplicate values are automatically ignored.

Main differences:

Characteristic	Array	Set
Order of elements	Preserved	Not guaranteed
Duplicates allowed	Yes	No
Access by index	Yes	No

Example in Swift:

var array = [1, 2, 2, 3] // contains duplicates
var set: Set = [1, 2, 2, 3] // contains only unique elements: 1, 2, 3

Choosing between an array and a set depends on the task: if order matters and duplicates are allowed — use an array; if uniqueness and fast lookup are needed — use a set.