Arrays · Tuck

An array is a numbered sequence of elements with a fixed length. The length is part of the type, so [5]int and [4]int are different types. In typical Go code, slices are much more common; arrays are useful in some special cases.

package main

import "fmt"

func main() {

This array holds exactly 5 ints. Elements start at the zero value, 0.

	var a [5]int
	fmt.Println("emp:", a)

Set and get a value with array[index].

	a[4] = 100
	fmt.Println("set:", a)
	fmt.Println("get:", a[4])

len returns the length of an array.

	fmt.Println("len:", len(a))

Declare and initialize an array in one line.

	b := [5]int{1, 2, 3, 4, 5}
	fmt.Println("dcl:", b)

... lets the compiler count the elements.

	b = [...]int{1, 2, 3, 4, 5}
	fmt.Println("dcl:", b)

An index with : sets that element; the ones in between are zeroed.

	b = [...]int{100, 3: 400, 500}
	fmt.Println("idx:", b)

Arrays are values: assigning one copies all of its elements.

	c := b
	c[0] = 0
	fmt.Println("copy:", b[0], c[0])

Arrays of the same type can be compared with ==.

	fmt.Println("equal:", [2]int{1, 2} == [2]int{1, 2})

Array types are one-dimensional, but you can compose them into multi-dimensional structures.

	var twoD [2][3]int
	for i := range 2 {
		for j := range 3 {
			twoD[i][j] = i + j
		}
	}
	fmt.Println("2d: ", twoD)

	twoD = [2][3]int{
		{1, 2, 3},
		{1, 2, 3},
	}
	fmt.Println("2d: ", twoD)
}

$ go run ./08_arrays
emp: [0 0 0 0 0]
set: [0 0 0 0 100]
get: 100
len: 5
dcl: [1 2 3 4 5]
dcl: [1 2 3 4 5]
idx: [100 0 0 400 500]
copy: 100 0
equal: true
2d:  [[0 1 2] [1 2 3]]
2d:  [[1 2 3] [1 2 3]]

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