2.6. Slices

Basics

With a slice literal (e.g. []int{1, 2, 3}) and the short assignment we we can initialize a new slice. Slices store multiple items of the same type.

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package main

import "fmt"

func main() {
	q := []int{2, 3, 5, 7, 11, 13}
	fmt.Println(q)
	fmt.Println("Length of slice:", len(q))
}

Output:
[2 3 5 7 11 13]
Length of slice: 6

Slice of structs

We can also store multiple instances of a struct.

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package main

import "fmt"

type Person struct {
	name string
	age  int
}

func main() {
	people := []Person{
		{name: "Christoph", age: 48},
		{name: "Susanne", age: 35},
		{name: "Peter", age: 29},
	}
	fmt.Println(people)
	fmt.Println(people[1])
}

Output:
[{Christoph 48} {Susanne 35} {Peter 29}]
{Susanne 35}

Appending items

To add items to an existing slice you can use append. Notice that append does not modify the original slice, but returns a new one.

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package main

import "fmt"

func main() {
	list := []int{1, 2, 3}
	fmt.Println("Initial slice:", list)

	// Add an item to a slice.
	list = append(list, 4)
	fmt.Println("Add one item:", list)

	// Add multiple items
	list = append(list, 5, 6, 7)
	fmt.Println("Add multiple items:", list)
}

Output:
Initial slice: [1 2 3]
Add one item: [1 2 3 4]
Add multiple items: [1 2 3 4 5 6 7]

Loops

In 2.2. Flow control we learned about the basic for loop. However if we want to loop over all the slice elements, we prefer to use range. With range we can iterate over all items of a slice.

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package main

import "fmt"

func main() {
	slice := []int{2, 4, 8}
	for index, item := range slice {
		fmt.Println(index, item)
	}
}

Output:
0 2
1 4
2 8

In many cases we discard the index with _ because we only need the actual item:

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package main

import "fmt"

func main() {
	slice := []int{2, 4, 8}
	for _, item := range slice {
		fmt.Println(item)
	}
}

Output:
2
4
8

2.6. Slices

Basics

Slice of structs

Appending items

Loops

Links