Code Formatting with gofmt

In this lesson, explore code formatting with gofmt through one small Go program, and connect its output to the language rules behind it.

gofmt applies Go’s standard formatting conventions. Run gofmt -w filename.go to rewrite files or gofmt -d filename.go to inspect changes.

Consistent formatting helps reviews focus on behavior. gofmt does not guarantee correct logic or detect every programming error.

Follow this diagram before executing the example. Check where a value or decision changes what runs next.

Use gofmt -w main.go, or run go fmt ./... for packages in the module.

This example is a complete program. Save it as main.go or paste it into the Go Playground.

Go code

package main

import "fmt"

func main() {
	numbers := []int{1, 2, 3}
	fmt.Println("Total:", numbers[0]+numbers[1]+numbers[2])
}

Output

Total: 6

The code formats with gofmt and computes 6. Whitespace and indentation changes do not alter the calculation.

• Do not manually align code in ways that fight gofmt.
• Formatting is not static analysis or unit testing.

Run gofmt -d on a deliberately misindented copy and compare the proposed changes.

Tip: Edit the example above, predict the output, and run the modified code to test your reasoning.

You have practiced Code Formatting with gofmt in a small, self-contained program. The important habit is to predict what runs, inspect the actual output and distinguish the language rule from the particular example.

Before continuing, make sure you can explain the program to someone who has not seen it, including the line that changes its result.