Go language: Slices are passed by reference

In Go language, Arrays are passed by value, whereas slices are passed by reference.

func updateCountries(countries []string) {

    countries[0] = "Dummy"

    countries[1] = "Dummy"

    countries[2] = "Dummy"

    countries[3] = "Dummy"

    countries[4] = "Dummy"

}

For example, if you call updateCountries method by passing a slice as an argument, the changes done for the slice ‘countries’ inside the method ‘updateCountries’ will be reflected outside.

App.go

package main

import "fmt"

func main() {
    countries := []string{}

    countries = append(countries, "India")
    countries = append(countries, "Bangladesh")
    countries = append(countries, "Canada")
    countries = append(countries, "Austria")
    countries = append(countries, "Germany")

    fmt.Println(countries)

    fmt.Println("\nUpdating countries with Dummy data")

    updateCountries(countries)

    fmt.Println()
    fmt.Println(countries)
}

func updateCountries(countries []string) {
    countries[0] = "Dummy"
    countries[1] = "Dummy"
    countries[2] = "Dummy"
    countries[3] = "Dummy"
    countries[4] = "Dummy"
}

Output

[India Bangladesh Canada Austria Germany]

Updating countries with Dummy data

[Dummy Dummy Dummy Dummy Dummy]

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