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Overview

Arrays in Go are fixed-size collections of elements of the same type. Unlike C, Go arrays are always zero-initialized, eliminating garbage memory vulnerabilities.
In Go, arrays are generally used when you need a fixed-size collection. For dynamic collections, use slices.

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Zero Initialization

One of Go’s safety features is guaranteed zero initialization. When you declare an array without explicitly setting values, Go automatically initializes all elements to their zero value.
In C, int a[5] contains garbage memory. In Go, it is always zeroed [0 0 0 0 0].

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Basic Array Declaration

Here’s how to declare and work with arrays in Go:
arrays/main.go
package main

import "fmt"

func main() {

	var nums [5]int //declaration of an array of integers with size 5

	fmt.Println("Initial array:", nums)
	fmt.Println(len(nums))

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

	fmt.Println("Two-dimensional array:", two)

}
Output: 
Initial array: [0 0 0 0 0]
5
Two-dimensional array: [[1 2 3] [4 5 6]]

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Key Characteristics

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Fixed Size

The size of an array is part of its type. An array of [5]int is a different type from [10]int. 
var nums [5]int  // Array of 5 integers
// Cannot resize - size is fixed at compile time
The len() function returns the length of the array, which is always the size specified at declaration.

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Multi-dimensional Arrays

Go supports multi-dimensional arrays for matrices and grids: 
two := [2][3]int{{1, 2, 3}, {4, 5, 6}}
// Creates a 2x3 array (2 rows, 3 columns)

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When to Use Arrays

Use arrays when:
  • You know the exact size at compile time
  • The size will never change
  • You need the performance benefit of stack allocation
  • You’re working with fixed-size data structures (e.g., RGB colors, coordinates)
For most use cases, Go developers prefer slices over arrays because slices are more flexible and idiomatic.

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Zero Values by Type

TypeZero Value
int, int8, int16, int32, int640
float32, float640.0
boolfalse
string"" (empty string)
Pointer typesnil
No ‘undefined’ errors. If you declare var nums [5]int but don’t set values, Go initializes each element to 0. No garbage memory.

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Next Steps

Arrays are the foundation for understanding slices, which are dynamic wrappers around arrays and the preferred way to work with collections in Go.

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