Sign in Get started

Go Tutorial · Go Basics · Lesson 3 of 30

Go Syntax

Packages, imports, functions, statements and Go's formatting rules.

Structure of a Go file

Example 1
package main

import (
	"fmt"
	"strings"
)

func greeting(name string) string {
	return "Hello, " + name
}

func main() {
	name := "Gopher"
	fmt.Println(greeting(name))
	fmt.Println(strings.Repeat("Go! ", 3))
}

Output

Hello, Gopher
Go! Go! Go!

Run this on your computer — see “Get Started” for setup.

  • package — every file belongs to a package; executables use package main.
  • import — the packages this file uses. Unused imports are a compile error, as are unused local variables — Go keeps code clean.
  • Functions are declared with func.
  • No semicolons at line ends (the compiler inserts them), and the opening brace { must be on the same line.

Exported names

A name starting with a capital letter is exported (visible outside its package): fmt.Println, strings.ToUpper. Lowercase names are private to the package.

gofmt

Go has one official formatting style, applied by gofmt (tabs for indentation). Editors run it on save, so all Go code looks the same.

Test yourself

What happens if you import a package but never use it?

  1. A warning
  2. A compile error
  3. Nothing
  4. A runtime panic
Show answer

Answer: A compile error