Go — Arrays

Arrays

Fixed-size collections:

package main

import "fmt"

func main() {
    var arr [5]int
    arr[0] = 10
    arr[1] = 20

    fruits := [3]string{"Apple", "Banana", "Cherry"}

    fmt.Println(arr)     // [10 20 0 0 0]
    fmt.Println(fruits)  // [Apple Banana Cherry]
    fmt.Println(len(arr)) // 5
}

Array operations

a := [3]int{1, 2, 3}
b := [3]int{4, 5, 6}

// Copy (arrays are value types)
c := a
c[0] = 100
fmt.Println(a) // [1 2 3] (unchanged)
fmt.Println(c) // [100 2 3]

// Compare
fmt.Println(a == b) // false

Slices

Dynamic-length views of arrays:

nums := []int{1, 2, 3, 4, 5}
slice := nums[1:3] // [2, 3]

fmt.Println(nums)  // [1 2 3 4 5]
fmt.Println(slice) // [2 3]

// Append
nums = append(nums, 6, 7)

// Make
data := make([]int, 5, 10) // len=5, cap=10

Slice operations

s := []int{1, 2, 3, 4, 5}

// Subslice
sub := s[1:3] // [2, 3]

// Copy
dst := make([]int, 3)
copy(dst, s[:3])

// Delete
s = append(s[:2], s[3:]...) // Remove index 2

// Reverse
for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
    s[i], s[j] = s[j], s[i]
}

Multi-dimensional arrays

matrix := [3][4]int{
    {1, 2, 3, 4},
    {5, 6, 7, 8},
    {9, 10, 11, 12},
}

fmt.Println(matrix[1][2]) // 7

Best practices

• Use slices over arrays in most cases
• Use make to pre-allocate when size is known
• Use append to grow slices dynamically
• Be aware that slices share underlying arrays

Mini Practice

Write Go code that:

1. Creates a slice and appends elements
2. Uses copy to duplicate a slice
3. Deletes an element from a slice
4. Creates a multi-dimensional array

Up Next

In the next lesson, you'll learn about Slices — Go's dynamic arrays in depth.