Arrays

What is it?

An Array is an ordered collection of values of the same type. You can store multiple items in a single variable and access them by their position (index). Arrays are written as [value1, value2, value3].

Why does it exist?

Arrays are essential when you need to work with multiple related items - like a list of names, a collection of numbers, or a series of user inputs. Instead of creating separate variables for each item (name1, name2, name3...), you can manage them all together in one array.

Examples

let fruits = ["Apple", "Banana", "Orange"]

var numbers = [1, 2, 3]
numbers.append(4)
let first = numbers[0]  // 1
let count = numbers.count  // 4

let numbers = [1, 2, 3, 4, 5]
let doubled = numbers.map { $0 * 2 }  // [2, 4, 6, 8, 10]
let evens = numbers.filter { $0 % 2 == 0 }  // [2, 4]

Common Mistakes

Common mistakes with arrays:
1. Wrong index: let items = ["a", "b"]; items[2] (Error! Index out of range)
2. Mixing types: let mixed = [1, "two", 3.0] (Error in typed languages!)
3. Forgetting arrays start at 0: First item is [0], not [1]
4. Modifying immutable arrays: let items = [1, 2]; items.append(3) (Error! Use 'var' instead)