Two-dimensional slices

Two-dimensional slices are descriptors of a two-dimensional array. A two-dimensional slice is a contiguous section of an array that is stored away from the slice itself. It holds references to an underlying array. A two-dimensional slice will be an array of arrays, while the capacity of a slice can be increased by creating a new slice and copying the contents of the initial slice into the new one. This is also referred to as a slice of slices. The following is an example of a two-dimensional array. A 2D array is created and the array elements are initialized with values.

twodarray.go is the code exhibit that's presented in the following code:

//main package has examples shown
// in Go Data Structures and algorithms book
package main
// importing fmt package
import (
 "fmt"
)
// main method
func main() {
 var TwoDArray [8][8]int
 TwoDArray[3][6] = 18
 TwoDArray[7][4] = 3
 fmt.Println(TwoDArray)
}

Run the following command:

go run twodarray.go

The following screenshot displays the output:

For dynamic allocation, we use slice of slices. In the following code, slice of slices is explained as two-dimensional slices—twodslices.go:

// in Go Data Structures and algorithms book
package main
// importing fmt package
import (
 "fmt"
)
// main method
func main() {
 var rows int
 var cols int
 rows = 7
 cols = 9
 var twodslices = make([][]int, rows)
 var i int
 for i = range twodslices {
 twodslices[i] = make([]int,cols)
 }
 fmt.Println(twodslices)
}

Run the following commands:

go run twodslices.go

The following screenshot displays the output:

 The append method on the slice is used to append new elements to the slice. If the slice capacity has reached the size of the underlying array, then append increases the size by creating a new underlying array and adding the new element. slic1 is a sub slice of arr starting from zero to 3 (excluded), while slic2 is a sub slice of arr starting from 1 (inclusive) to 5 (excluded). In the following snippet, the append method calls on slic2 to add a new 12 element (append_slice.go):

var arr = [] int{5,6,7,8,9}
var slic1 = arr[: 3]
fmt.Println("slice1",slic1)
var slic2 = arr[1:5]
fmt.Println("slice2",slic2)
var slic3 = append(slic2, 12)
fmt.Println("slice3",slic3)

Run the following commands:

go run append_slice.go

The following screenshot displays the output:

Now that we have covered what two-dimensional slices are, let's take a look at maps in the next section.