Arrays & Slices

In Go, there are two ways to store collections of data: Arrays and Slices. What's the difference?

1. Array (Rarely Used)

Arrays have a fixed size. If you create an array [5]int, you cannot adds a 6th element.

Pros: Memory efficient, fast.

Cons: Not flexible.

2. Slice (Commonly Used)

A Slice is a dynamic "window" into an array. Its size can change (expand or shrink).

Pros: Highly flexible.

Function: append() to add data.

When to use?

In almost 99% of cases in Go, you will use a Slice. Use an Array only if you know for sure the number of items will never change (e.g., the 7 Days of the week).

MAIN.GO

package main
import "fmt"
func main() {
    // Array: FIXED size [2]
    var arr [2]int
    arr[0] = 100
    arr[1] = 200
    fmt.Println("Array:", arr)
    // Slice: DYNAMIC size [] (empty brackets)
    primes := []int{2, 3, 5, 7}
    fmt.Println("Initial Slice:", primes)
    // Adding new data to the slice using append
    primes = append(primes, 11)
    fmt.Println("New Slice:", primes)
}