Slice is a reference to a continuous fragment of an array (which we call the relevant array, usually anonymously), so the slice is a reference type (not the same as an array).

This fragment can be an entire array, or a subset of some items identified by the originating and terminating index. The format of a slice is array[start:end].

Slice

What is a slice?

The slice provides a dynamic window of an array (a slice is to an array as a slice is to a pizza) The items identified by the terminating index are not included in the slice.

However, unlike the array: the length of the slice can be modified at run time, with a minimum of zero maximum of the length of the array

The length of the slice will never exceed its capacity, so that the inequality is always true for slices: 0 <= len (s) <= cap (s).

Attention Never use a pointer to point to the slice, the slice itself is already a reference type, so it is itself a pointer!

Go syntax

The format of the declaration slice is: var identifier [] type (no description length required).

One slice defaults to nil before it is initialized and its length is 0.

The initialization format of the slice is:

var slice1 []type = arr1[start:end]

This means that the slice1 is a subset of elements from the start index to the end-1 index (split array, start:end known as the slice expression) from the start index to the end-1 index.

Slice can also be initialized in a similar array:

var x = []int{2, 3, 5, 7, 11}

This creates an array of length 5 and creates a related slice.

When the relevant array is not yet defined, we can use the make() function to create a slice while creating a good correlation array:

var slice1 []type = make([]type, len)

It can also be abbreviated to slice1 := make([] type, len), where len is the length of the array and also the initial length of the slice.

The make use mode is: func make([] T, len, cap) where cap is an optional parameter.

v := make([]int, 10, 50)

This allocates an array with a 50 int value, and creates a slice v with a length of 10 with a capacity of 50, which points to the first 10 elements of the array.

We have listed three types of slice initialization, which are common in all three ways.

Example

If you generate a new slice from an array or slice, we can use the following expression:

a[low : high : max]

Example:

package main

import "fmt"

func main() {
    // define array
    a := [5]int{1, 2, 3, 4, 5}

    // create slice from array
    t := a[1:3:5]

    // output slice
    fmt.Println(t)
}

[2 3]

Program exited.

Because slices are referenced, they do not need to use extra memory and are more efficient than using arrays, so slices in Go code are more common than arrays.