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Slices

Slices are like arrays but have a more dynamic nature and can grow and shrink over time.

Slices don't actually hold their own data, a slice always refers to data somewhere in some array, known as reference data types. 

Array:

INDEX:   0   1   2   3   4   5   6   7   8   9
VALUES: 463 234 757 123 645 434 345 908 456 825 

Slice:
INDEX:              0   1   2   3   4
VALUES:            757 123 645 434 345

Changing a values in the underlying array will be reflected in the slice and vise versa.

Initialize slice

To declare a slice we use the same syntax as defining an array but without specifying the number of elements.

main.go
package main

import "fmt"

func main() {
    var mySlice []int
    fmt.Println(mySlice)
}

An empty slice is initialized and contains nil, remember they don't hold there own data they hold memory address that point to data somewhere else in memory.

Populating slice

Just like when working with arrays, you can define initial values:

main.go
package main

import "fmt"

func main() {
    mySlice := []int{10, 20, 30, 40, 50}
    fmt.Println(mySlice)
}

Accessing slice

Like arrays, you can access specific elements:

main.go
package main

import "fmt"

func main() {
    mySlice := []int{10, 20, 30, 40, 50}
    fmt.Println(mySlice[3])
}

Modify slice

Likewise, you can modify specific elements:

main.go
package main

import "fmt"

func main() {
    mySlice := []int{10, 20, 30, 40, 50}
    fmt.Println(mySlice[3])
    mySlice[3] = 42
    fmt.Println(mySlice[3])
}

Copy slice

Unlike with arrays when you make a copy fo a slice, the data change in one will be reflecting in the other because the elements are pointers.

main.go
package main

import (
    "fmt"
)

func main() {
    mySlice := []int{10, 20, 30, 40, 50}
    myNumbers := mySlice

    mySlice[3] = 42

    fmt.Println(mySlice)
    fmt.Println(myNumbers)
}

Output:

[10 20 30 42 50]
[10 20 30 42 50]

Append to slice

Unlike with an array, slices have an append function:

main.go
package main

import "fmt"

func main() {
    mySlice := []int{10, 20, 30, 40, 50}
    mySlice = append(mySlice, 60, 70, 80, 90)
    fmt.Println(mySlice)
}

Output:

[10 20 30 40 50 60 70 80 90]

Deleting from slice

Removing elements, need to number the start index and the end index, up to and not including (unless it's the last element):

main.go
package main

import (
    "fmt"
    "slices"
)

func main() {
    mySlice := []int{10, 20, 30, 40, 50}
    mySlice = append(mySlice, 60, 70, 80, 90)
    fmt.Println(mySlice)
    mySlice = slices.Delete(mySlice, 5, 9)
    fmt.Println(mySlice)
}