Why arrays are needed in Go

Introduction

Arrays help us store many items together in one place. This makes it easy to keep and use a list of things.

When you want to keep a list of student names in a class.

When you need to store daily temperatures for a week.

When you want to save scores of players in a game.

When you want to remember multiple phone numbers.

When you want to process a group of items one by one.

Syntax

Go

package main

import "fmt"

func main() {
    var numbers [5]int // array of 5 integers
    numbers[0] = 10    // set first item
    numbers[1] = 20    // set second item
    fmt.Println(numbers) // print the whole array
}

An array has a fixed size, set when you create it.

You access items by their position, starting at 0.

Examples

This creates an array of 3 integers, all set to zero by default.

Go

var emptyArray [3]int
fmt.Println(emptyArray)

An array with only one item can still be useful to hold a single value in a list form.

Go

var singleElementArray [1]string
singleElementArray[0] = "hello"
fmt.Println(singleElementArray)

This creates and fills an array with 3 fruit names right away.

Go

var fruits = [3]string{"apple", "banana", "cherry"}
fmt.Println(fruits)

Sample Program

This program shows how to create an array, store values, and get values by position.

Go

package main

import "fmt"

func main() {
    // Create an array to store 4 temperatures
    var temperatures [4]int

    // Set values for each day
    temperatures[0] = 70
    temperatures[1] = 72
    temperatures[2] = 68
    temperatures[3] = 65

    // Print all temperatures
    fmt.Println("Temperatures for 4 days:", temperatures)

    // Access one day's temperature
    fmt.Println("Temperature on day 2:", temperatures[1])
}

Important Notes

Arrays have a fixed size, so you cannot add more items than the size.

Accessing an array item by index is very fast (constant time).

Common mistake: Trying to access an index outside the array size causes an error.

Use arrays when you know the number of items in advance and it won't change.

Summary

Arrays store multiple items together in one variable.

They have a fixed size set when created.

Use arrays to keep lists of things you want to access by position.