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:

The following code demonstrates the use of the append function:

index


              1234
            
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


              1
            
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


              12
            
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


              1
            
arrayName[startingIndex:endingIndex + 1]

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

index


              123
            
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


              12345678910111213
            
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]
}

Everything was clear?

Thanks for your feedback!

Section 5. Chapter 3