Help with pointers...https://play.golang.org/p/Inn0fgn1H23

Getting Help
1

https://play.golang.org/p/Inn0fgn1H23

Why does fmt.Println(*&j) produce 39, but if I change j to k : https://play.golang.org/p/9qblZnxweVL
I get 0x414020 ?

Seemingly similarly, if I change j to k : https://play.golang.org/p/fvHT8SEtb-J
https://play.golang.org/p/tPdIL7Ld3o5
I get the address rather than the value. Why?

2

k is actually an int pointer data-type, which is *int. It holds the j memory address as value when you set it ( at this line:k := &j).

To access the value from the given pointer, you append the asterisk before a pointer memory address (e.g. a pointer like &j or &k) or pointer variable holding the memory address (e.g.: k). Example:

	j := 39
	k := &j   // k is *int

	fmt.Printf("j variable             : %v\n", j)
	fmt.Printf("j pointer              : %v\n", &j)
	fmt.Printf("j pointed value        : %v\n", *&j)
	fmt.Printf("k variable             : %v\n", k)
	fmt.Printf("k pointer              : %v\n", &k)
	fmt.Printf("k value's pointed value: %v\n", *k)
	fmt.Printf("k pointed value        : %v\n", *&k)

You will see that the output is:

j variable             : 39
j pointer              : 0x414020
j pointed value        : 39
k variable             : 0x414020
k pointer              : 0x40c138
k value's pointed value: 39
k pointed value        : 0x414020

Notice that when you access the value of k memory address: *(&k), it returns the value of k instead.

Playground: Go Playground - The Go Programming Language

So when you change the last printout from fmt.Println(*&j) to fmt.Println(*&k), it simply means:

Access the pointed value given by the k variable's memory address.

This is why you get a memory address instead of a value. To get back the 39, you change it to *k,
which says:

Access the pointed value from the given pointer variable's value:
the stored memory address.
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