Golang in sixty seconds — Pointers

A pointer is the location in memory where a value lives. It's very important in Go to understand pointers as most parameters given to functions will be passed by value, not reference. This means that the following code may not do what you expect it to:

func add1(num int) {
  num = num+1
}
myNum := 1
add1(myNum)
fmt.Println(myNum)

This will print “1” to the console (you can try it here). A copy of myNum is made when it is passed to the function add1. So now there are two memory locations with a value of 1. The one used in the function will be updated to 2, but the original myNum stays the same. If we want the function to mutate myNum we must use pointers like so:

func add1(num *int) {
  *num = *num+1
}
myNum := 1
add1(&myNum)
fmt.Println(myNum)

All those asterisk's and ampersands are confusing, right? You can try ithere

Here's the cheat sheet I use to help me on a daily basis:

Other stories about Golang:

Learn Golang with me - Playing with Time

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15 Oct 2021

Golang in sixty seconds - scope

Understanding where your variables can be used from

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Golang in sixty seconds - function basics

Learn the basics of functions in Golang

04 Aug 2022

Golang in sixty seconds - defer

Golang has a special statement called defer which causes the function to be run after the function completes.

09 Aug 2022

Golang in sixty seconds - folders and packages

How to structure your Golang code into folders

28 Jan 2022

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