Basic

A dynamically sized view into an array.

They do not store data, they just reference an array

func main() {
	a := [7]int{0, 1, 2, 3, 4, 5, 6}

	slice := a[1:4]
	a[1] = 2

	fmt.Println(slice)
}

// Output: [2 2 3]

A slice can manipulate the underlying data structure

func main() {
	a := [7]int{0, 1, 2, 3, 4, 5, 6}

	slice := a[1:4]
	a[1] = 2
	slice[1] = 10

	fmt.Println(slice)
}

The normal way of defining a slice

This will create an array, then create a slice onto it, which you can then use as a

func main() {
	a := []int{0, 1, 2, 3, 4, 5, 6}

	fmt.Printf("%T, %v", a, a)
}

Access

func main() {
	a := []int{0, 1, 2, 3, 4, 5, 6}

	fmt.Printf("%v\n", a[:3])
	fmt.Printf("%v\n", a[3])
	fmt.Printf("%v\n", a[:])
	fmt.Printf("%v\n", a)
}

/* 
Output:
	[0 1 2]
	3
	[0 1 2 3 4 5 6]
	[0 1 2 3 4 5 6]
*/

Capacity vs Length

Capacity is the length of the underlying array

The length is just the length of the slice

Note: Thus you can index out of range if you are not looking at the capacity

func main() {
	a := []int{0, 1, 2}

	fmt.Printf("Length %v\n", len(a))
	fmt.Printf("Capacity %v\n", cap(a))

	a[10] = 1
}

/* 
Output:
	Length 3
	Capacity 3
	panic: runtime error: index out of range [10] with length 3
*/

Nil slice

A slice with 0 capacity and length

func main() {
	var a []int

	fmt.Printf("Length %v\n", len(a))
	fmt.Printf("Capacity %v\n", cap(a))

	if a == nil {
		fmt.Println("Is Nil")
	}
}

/*
Output:
	Length 0
	Capacity 0
	Is Nil
*/