Go Arrays

Go Arrays #

Arrays are used to store multiple values of the same type in a single variable, instead of declaring separate variables for each value.

Declaring an Array #

In Go, there are two ways to declare an array:

1. Using the var keyword #

var array_name = [length]datatype{values} // length defined
var array_name = [...]datatype{values}    // length inferred

2. Using the := shorthand #

array_name := [length]datatype{values} // length defined
array_name := [...]datatype{values}    // length inferred

Note: Arrays in Go have a fixed length. The length is either explicitly defined or inferred from the number of values.

Array Examples #

Defined Length #

package main
import ("fmt")

func main() {
  var arr1 = [3]int{1,2,3}
  arr2 := [5]int{4,5,6,7,8}

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

Result:

[1 2 3]
[4 5 6 7 8]

Inferred Length #

package main
import ("fmt")

func main() {
  var arr1 = [...]int{1,2,3}
  arr2 := [...]int{4,5,6,7,8}

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

Result:

[1 2 3]
[4 5 6 7 8]

Array of Strings #

package main
import ("fmt")

func main() {
  var cars = [4]string{"Volvo", "BMW", "Ford", "Mazda"}
  fmt.Print(cars)
}

Result:

[Volvo BMW Ford Mazda]

Access Elements of an Array #

Array indexes start at 0. To access elements:

package main
import ("fmt")

func main() {
  prices := [3]int{10,20,30}

  fmt.Println(prices[0]) // first element
  fmt.Println(prices[2]) // third element
}

Result:

10
30

Change Elements of an Array #

package main
import ("fmt")

func main() {
  prices := [3]int{10,20,30}
  prices[2] = 50
  fmt.Println(prices)
}

Result:

[10 20 50]

Array Initialization #

Uninitialized arrays are assigned default values:

package main
import ("fmt")

func main() {
  arr1 := [5]int{}          // not initialized
  arr2 := [5]int{1,2}       // partially initialized
  arr3 := [5]int{1,2,3,4,5} // fully initialized

  fmt.Println(arr1)
  fmt.Println(arr2)
  fmt.Println(arr3)
}

Result:

[0 0 0 0 0]
[1 2 0 0 0]
[1 2 3 4 5]

Initialize Specific Elements #

package main
import ("fmt")

func main() {
  arr1 := [5]int{1:10,2:40}
  fmt.Println(arr1)
}

Result:

[0 10 40 0 0]

Explanation:

  • 1:10 assigns 10 to index 1 (second element)
  • 2:40 assigns 40 to index 2 (third element)

Find the Length of an Array #

package main
import ("fmt")

func main() {
  arr1 := [4]string{"Volvo", "BMW", "Ford", "Mazda"}
  arr2 := [...]int{1,2,3,4,5,6}

  fmt.Println(len(arr1))
  fmt.Println(len(arr2))
}

Result:

4
6

Tip: The len() function returns the number of elements in an array.

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