pointers.go

package main

import (
	"fmt"
)

/*
We’ll show how pointers work in contrast to values with 2 functions:
zeroval and zeroptr. zeroval has an int parameter, so arguments will
 be passed to it by value. zeroval will get a copy of ival distinct
 from the one in the calling function.
*/
func zeroval(ival int) {
	ival = 0
}

/*
zeroptr in contrast has an *int parameter,
meaning that it takes an int pointer.
The *iptr code in the function body then dereferences the pointer
from its memory address to the current value at that address.
Assigning a value to a dereferenced pointer changes the value at
the referenced address.
*/
func zeroptr(iptr *int) {
	*iptr = 0
}
func main() {
	i := 1
	fmt.Println("initial:", i)

	zeroval(i)
	fmt.Println("zeroval:", i)
	//The &i syntax gives the memory address of i, i.e. a pointer to i.
	zeroptr(&i)
	fmt.Println("zeroptr:", i)
	//Pointers can be printed too.
	fmt.Println("pointer:", &i)
	//zeroval doesn’t change the i in main, but zeroptr does
	//because it has a reference to the memory address for that variable.
}