Slices

Slices are akin to arrays, but they possess dynamic lengths, making them a more flexible alternative to arrays.

To create a slice, we utilize the same syntax as for arrays, but in this case, we omit specifying the size.

Creating a slice using the var keyword:


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// Creates an empty slice with no elements
var sliceName [] dataType

// Creates a slice with the specified elements
var sliceName = [] dataType {element_1, element_2, ...}

Create a Slice using the := operator:


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// Creates a slice with the specified elements
sliceName := [] dataType { element_1, element_2, ... }

We can add additional elements to a slice using the append function. The append function returns a new slice with the appended elements, which we can then store in the original slice variable. This will become clearer with an example. The basic syntax of the append function is as follows:


append(originalSlice, newElement1, newElement2, …)

The following code demonstrates the use of the append function:

index.go

randomNumbers := [] int { 1, 4, 5}

fmt.Println(randomNumbers) // Output: [1 4 5]

randomNumbers = append(randomNumbers, 7, 9)

fmt.Println(randomNumbers) // Output: [1 4 5 7 9]


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randomNumbers := [] int { 1, 4, 5}
fmt.Println(randomNumbers) // Output: [1 4 5]
randomNumbers = append(randomNumbers, 7, 9)
fmt.Println(randomNumbers) // Output: [1 4 5 7 9]

In the same way that we can access elements within an array, we can also reference portions of an array using the following syntax:

index.go

arrayName[startIndex:endIndex + 1]


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arrayName[startIndex:endIndex + 1]

It will extract all elements from the startingIndex to the endingIndex. Please note that we need to provide endingIndex + 1. This will become clearer with an example. For example:

index.go

var numbers = [10] int { 2, 4, 6, 9, 10, 12, 14, 16, 17, 19 }

fmt.Println(numbers[4:9]) // Output: [10 12 14 16 17]


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var numbers = [10] int { 2, 4, 6, 9, 10, 12, 14, 16, 17, 19 }
fmt.Println(numbers[4:9]) // Output: [10 12 14 16 17]

It extracts the elements from indexes 4 to 9, including the element at index 4 and excluding the element at index 9, as expressed in the syntax:

index.go

arrayName[startingIndex:endingIndex + 1]


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arrayName[startingIndex:endingIndex + 1]

We can also store this extracted portion of the array in a variable, thus creating a slice:

index.go

var numbers = [10] int { 2, 4, 6, 9, 10, 12, 14, 16, 17, 19 }

numbersPart := numbers[2:7]

fmt.Println(numbersPart) // Output: [6 9 10 12 14]


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var numbers = [10] int { 2, 4, 6, 9, 10, 12, 14, 16, 17, 19 }
numbersPart := numbers[2:7]
fmt.Println(numbersPart) // Output: [6 9 10 12 14]

It's important to note that such a slice references the portion of the array from which it was created. Consequently, any changes made in that slice will also affect the original array:

index.go

package main

import "fmt"

func main() {

var pin = [4] int { 1, 2, 3, 4 }

part := pin[1:3]

fmt.Println(pin) // Output [1, 2, 3, 4]

fmt.Println(part) // Output: [2, 3]

part[0] *= 2

part[1] *= 3

fmt.Println(part) // Output [4, 9]

fmt.Println(pin) // Output [1, 4, 9, 4]

}


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package main
import "fmt"

func main() {
    var pin = [4] int { 1, 2, 3, 4 }
    part := pin[1:3]
    fmt.Println(pin) // Output [1, 2, 3, 4]
    fmt.Println(part) // Output: [2, 3]
    part[0] *= 2
    part[1] *= 3
    fmt.Println(part) // Output [4, 9]
    fmt.Println(pin) // Output [1, 4, 9, 4]
}

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