Pointers

Context

A pointer holds the memory address of a value. Use *T for a pointer to a T, and & to get the address. Go has no pointer arithmetic (except via unsafe).

Example

Pass by value vs by reference.

Code example

package main

import "fmt"

func zeroVal(x int) {
    x = 0
}

func zeroPtr(x *int) {
    *x = 0
}

func main() {
    a := 42
    zeroVal(a)
    fmt.Println(a)      // still 42

    zeroPtr(&a)
    fmt.Println(a)      // now 0

    // nil pointers
    var p *int
    if p == nil {
        fmt.Println("p is nil")
    }
}

Output

42
0
p is nil

Useful links

• Go by Example: Pointers
• Go spec: Pointer types