Go Pointers

A pointer holds the address of a value. &x takes the address; *p reads or writes through a pointer. Go passes arguments by value, so use a pointer when a function must change the caller's variable.

ExampleGo

package main

import "fmt"

func addOne(n int) { n++ }
func addOnePtr(n *int) { *n++ }

type Counter struct{ Count int }

func main() {
  x := 10
  addOne(x)
  fmt.Println(x) // 10: only a copy changed
  addOnePtr(&x)
  fmt.Println(x) // 11

  p := &x
  *p = 50
  fmt.Println(x, *p)

  c := &Counter{}
  c.Count++ // Go follows the pointer for you
  fmt.Println(c.Count)

  var none *int
  fmt.Println(none == nil)
}

Output

10
11
50 50
1
true

Quick check

Why pass a pointer to a function?

So the function can change the original valueTo make the code shorterGo requires it for ints

Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.

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