Golang maps are reference types

maps_as_references.go

package main

import "fmt"

// Function tp update maps
func updateNumbers(m map[string]int) {
	m["three"] = 3
	m["four"] = 4
}

func main() {

	veggies := map[string]int{
		"onion":   12,
		"cabbage": 15,
	}
	veggies["orka"] = 90
	// Returns Original veggies map map[onion:12 cabbage:15 orka:90]
	fmt.Println("Original veggies map", veggies)

	newVeggies := veggies
	newVeggies["orka"] = 180
	// Returns New Veggies map map[cabbage:15 orka:180 onion:12]
	fmt.Println("New Veggies map", newVeggies)

	// Returns Updated veggies map[onion:12 cabbage:15 orka:180]
	fmt.Println("Updated veggies", veggies)

	// Passing map to a function
	numbers := make(map[string]int)
	numbers["one"] = 1
	numbers["two"] = 2

	// Returns numbers map[one:1 two:2]
	fmt.Println("numbers", numbers)

	// Add elements to the map in the function
	updateNumbers(numbers)

	// Returns after numbers are updated map[one:1 two:2 three:3 four:4]
	fmt.Println("after numbers are updated", numbers)

}