How to assign a new object to a reference?

Question

Why can't I do it like this in Go?

func do(m1 map[int]string) {
    var m map[int]string = make(map[int]string)
    *m1 = &m;
}

I have m1 map, which means I can now it's reference? How to assign a new object to that memory pointer?

m1 is not a pointer type, so you can not use * to access its value. — mrasoolmirza
– mrasoolmirza, Commented Sep 4 at 15:08

Burak Serdar · Accepted Answer · 2025-09-04 15:04:57Z

2

m1 is a map, and it is passed by value to the function do. That is, where the function is called, a copy of another map variable is passed. The fact that a map is a pointer type is irrelevant here. A copy of that pointer is passed.

If you want to change the map at the call site, you have to pass it as pointer:

func do(m1 *map[int]string) {
    var m map[int]string = make(map[int]string)
    *m1 = m;
}

answered Sep 4 at 15:04

Burak Serdar

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