[Author: @mdimamhosen Date: 2025-04-19 Category: interview-qa/arrays Tags: [go, arrays, functions] ]

Arrays in Go

Declaring Arrays

You can declare an array in Go using the following syntax:

var arrayName [size]elementType

Example:

var numbers [5]int

Initializing Arrays

Arrays can be initialized at the time of declaration:

var numbers = [5]int{1, 2, 3, 4, 5}

Or you can use the shorthand notation:

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

Accessing Array Elements

Array elements are accessed using the index, which starts from 0:

fmt.Println(numbers[0]) // Output: 1

Iterating Over Arrays

You can iterate over arrays using a for loop:

for i := 0; i < len(numbers); i++ {
    fmt.Println(numbers[i])
}

Or using the range keyword:

for index, value := range numbers {
    fmt.Println(index, value)
}

Multidimensional Arrays

Go supports multidimensional arrays. A two-dimensional array is declared as follows:

var matrix [3][3]int

Example:

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

Array of Arrays

You can also create an array of arrays:

var arrayOfArrays [2][3]int

Example:

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

Passing Arrays to Functions

Arrays can be passed to functions by value, meaning the function receives a copy of the array:

func printArray(arr [5]int) {
    for i := 0; i < len(arr); i++ {
        fmt.Println(arr[i])
    }
}

To modify the original array, you can pass a pointer to the array:

func modifyArray(arr *[5]int) {
    arr[0] = 100
}

Frequently Asked Questions

Q1: How can I find the length of an array in Go?

You can use the built-in len() function to find the length of an array.

Example:

package main

import "fmt"

func main() {
    arr := [5]int{1, 2, 3, 4, 5}
    fmt.Println("Length of the array:", len(arr)) // Output: 5
}

Q2: How do I copy an array in Go?

In Go, you can copy an array by simply assigning it to another array of the same type and size.

Example:

package main

import "fmt"

func main() {
    original := [3]int{1, 2, 3}
    copy := original
    fmt.Println("Original:", original) // Output: [1 2 3]
    fmt.Println("Copy:", copy)         // Output: [1 2 3]
}

Q3: How can I pass an array to a function without copying it?

To avoid copying, you can pass a pointer to the array.

Example:

package main

import "fmt"

func modifyArray(arr *[3]int) {
    arr[0] = 42
}

func main() {
    arr := [3]int{1, 2, 3}
    modifyArray(&arr)
    fmt.Println("Modified array:", arr) // Output: [42 2 3]
}

Example code to test: main.go

package main

import "fmt"

func main() {
	arr1 := [5]int{1, 2, 3, 4, 5}
	arr2 := [5]int{1, 2, 3, 4, 5}

	fmt.Println(arr1)
	fmt.Println(arr2)

	var arr3 [5]int
	// fmt.Println(arr3) // this should print [0 0 0 0 0]
	// println("Length:", len(arr3))

	for i := 0; i < len(arr3); i++ {
	    fmt.Scan(&arr3[i])
	}
	fmt.Println(arr3)

	strArr := [3]string{"one", "two", "three"}

	for i := 0; i < len(strArr); i++ {
		fmt.Print(strArr[i]+ "")
	}


}