/**
* Go: passing a pointer allows function to change the
* value of this thing being pointed at.   This gives go a
* backdoor return value.   In some langs (eg C) this is very
* useful, given multi-return in Go, not as much
*
* @author gtowell
* Created August 2021
 */

package main

import "fmt"

func main() {
	aa := 3
	aap := &aa
	fmt.Printf("IN MAIN: %d %p %d\n", aa, aap, *aap)
	passer(aap)
	fmt.Printf("IN MAIN: %d %p %d\n", aa, aap, *aap)
}

func passer(poi *int) {
	fmt.Printf("IN PASSERa %p %d\n", poi, *poi)
	*poi = 5
	qq := 7
	fmt.Printf("IN PASSERb %p %d\n", poi, *poi)
	// changing the thing pointed to by poi
	// does NOT change the pointer outside the function.
	// pointer is passed by value
	poi = &qq
	qq = 9
	fmt.Printf("IN PASSERc %p %d\n", poi, *poi)
}