Writing nil-Safe Code (Checking a Pointer for nil)

In this lesson you will learn to handle values safely against nil in Go, avoiding errors when a value has not been set. This is for anyone searching for "Go nil handling".

Go uses nil to represent the absence of a value (for pointers, slices, maps, and more). Checking with == nil before use is the basic discipline.

The sample code checks whether the pointer declared as var address *string is nil using if address == nil, printing "No address set" when there is no value. Dereferencing a nil pointer crashes the program, so this check is a habit in real Go code.

A common stumbling block for beginners is dereferencing without checking, as in *address. That is one of the classic causes of a runtime panic. It is also characteristically Go that reading from a nil slice or map is usually safe and simply behaves as empty.

In real-world development, allowing for values from a database or an API being empty, and writing nil-safe code to head off errors, is taken seriously.

📖 Reference code

package main

import "fmt"

func main() {
    var address *string
    if address == nil {
        fmt.Println("No address set")
    } else {
        fmt.Println(*address)
    }
}

✍️ Your code

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🧪 This site can't compile or run Go directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).