pass_by_value.go

package main

func changeMap(m1 *map[string]int) {
	m1 = &map[string]int{"hello": 2}
}

func changeMap2(m2 *map[string]int) {
	*m2 = map[string]int{"hello": 2} // without dereferencing, Go cannot achieve this
}

func changeMap3(m3 map[string]int) {
	m3 = map[string]int{"hello": 2} 
}

func main() {
	m1 := map[string]int{"hello": 1}
	changeMap(&m1)
	println(m1["hello"]) // 1

	m2 := map[string]int{"hello": 1}
	changeMap2(&m2)
	println(m2["hello"]) // 2

	m3 := map[string]int{"hello": 1}
	changeMap3(m3)
	println(m3["hello"]) // 1
}