Why is the struct field value forgotten

http://play.golang.org/p/wU44VOa_uP

Here's a simple example:

package main

import "fmt"

type Holder struct {
	i int
}

func (h Holder) SetMember(i1 int) {
	fmt.Println(i1)
	h.i = i1
}

func (h Holder) GetMember() int {
	fmt.Println(h.i)
	return h.i
}

func main() {
	c := Holder{i:3}
	c.SetMember(5)
	c.GetMember()
}

I'm probably missing a very basic truth about golang.
Why doesn't the value 5 stick after setting it?

This example works:
http://play.golang.org/p/j8hdKWPdsc

package main

import "fmt"

type Holder struct {
	i int
}

func (h *Holder) SetMember(i1 int) {
	fmt.Println(i1)
	h.i = i1
}

func (h *Holder) GetMember() int {
	fmt.Println(h.i)
	return h.i
}

func main() {
	c := &Holder{i:3}
	c.SetMember(5)
	c.GetMember()
}

In the second example you passing the struct object itself, you are a pointer receiver. You see the change because you have actually modified the original object. In the first example you are passing the copy of the object that contains the same values, you are using a value receiver. You don't see the change because your original object was not changed.

To convince yourself, you can print the addresses of the objects inside main and your SetMember method.

When using pointer receiver:

In main:

fmt.Printf("address in main: %p\n", c)

In SetMember (should be the same as in main):

fmt.Printf("address in SetMember: %p\n", h)

When using value receiver:

In main:

fmt.Printf("address in main: %p\n", &c)

In SetMember (should be different from what is in main) :

fmt.Printf("address in SetMember: %p\n", &h)