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Comments and semicolons

Learn // and /* */ comments and the semicolon rule in Go.

Comments

Go has two kinds of comments: single-line (//) and multi-line (/* ... */). The compiler ignores comments; they are used for explanation and notes.

A single-line comment runs from // to the end of the line. A multi-line comment starts with /* and ends with */; it can span several lines.

Good comments explain the intent; they say why, not what. Avoid comment clutter.

Automatic semicolons

The Go compiler automatically inserts semicolons at line ends. So most lines do not end with a semicolon. If you write one, it does not cause an error but Go tools will strip it.

You can write a semicolon by hand when really needed (e.g. multiple statements on one line). But Go style keeps one statement per line.

This automatic behavior works in harmony with gofmt; running gofmt -w keeps your code consistent.

Practice Add a comment and output

Add a // comment to the program and produce the output Go is great with fmt.Println.

Starter code

main.go
package main

import "fmt"

func main() {
    return
}

Sample solution

main.go
package main

import "fmt"

func main() {
    // Information
    fmt.Println("Go is great")
}

Expected output

Go harika

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Which starts a single-line comment in Go?

  • #
  • --
  • // Correct answer
  • ;

Explanation: // starts a single-line comment in Go.

2 Single-line comment

Question 
// Score ____ 90
Answer 
// Score value: 90

Explanation: 'value:' is an explanatory note inside a comment.

3 Match the comment kinds

Term Meaning
// Single-line comment
/* */ Multi-line comment
gofmt Code formatter
comments Ignored by the compiler

All lessons in Beginner

1 Go basics

  1. What is Go?
  2. Installing Go
  3. Your first program
  4. go run and go build
  5. Comments and semicolons
  6. Summary - Go basics

2 Modules

  1. go mod init
  2. package and import
  3. The main package
  4. Multiple files
  5. go.sum and dependencies
  6. Summary - Modules

3 Variables

  1. Declaration with var
  2. Short declaration :=
  3. const and iota
  4. Zero value
  5. Type inference
  6. Summary - Variables

4 Data types

  1. int and float
  2. bool and string
  3. byte and rune
  4. Type conversion
  5. Type definitions
  6. Summary - Data types

5 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Command-line menu

6 Functions

  1. func declaration
  2. Parameters and return
  3. Multiple return
  4. Variadic functions
  5. Anonymous functions
  6. Summary - Functions

7 Control flow

  1. if, else if, else
  2. for loop
  3. Iterating with range
  4. switch and fallthrough
  5. break and continue
  6. Summary - Control flow

8 Array and slice

  1. Array declaration
  2. Slice declaration
  3. Appending with append
  4. Sub-slice
  5. len and cap
  6. Summary - Array and slice

9 Project: Shopping cart

  1. Product struct
  2. Adding to cart
  3. Computing total
  4. Printing the cart

10 Map

  1. Map declaration
  2. Adding elements
  3. Looking up in a map
  4. Deleting from a map
  5. Iterating a map with range
  6. Summary - Map

11 String

  1. String and byte
  2. String concatenation
  3. Conversion with strconv
  4. The strings package
  5. Rune and UTF-8
  6. Summary - String

12 Pointer

  1. What is a pointer?
  2. & and * operators
  3. The new function
  4. Pointers and functions
  5. Nil pointer
  6. Summary - Pointer

13 Struct

  1. Struct declaration
  2. Creating a struct
  3. Field access
  4. Struct embedding
  5. Struct and pointer
  6. Summary - Struct

14 Methods

  1. Method declaration
  2. Pointer receiver
  3. Value receiver
  4. Methods and embedding
  5. Method chaining
  6. Summary - Methods

15 Interface and error

  1. Interface declaration
  2. Implicit satisfaction
  3. The error interface
  4. Returning errors
  5. errors.Is and errors.As
  6. Summary - Interface and error

16 Beginner final

  1. Challenge 1 - Combined program
  2. Challenge 2 - Data structure
  3. Challenge 3 - Error handling
  4. Challenge 4 - Mini app