Example of Adding Comments in 15 Programming Languages

Let’s find out what are comments and why they are important in programming.

We also cover two common types of comments and how to write them in 15 different programming languages.

What are comments in programming?

Comments in layman terms are pieces of text that will not be visible to end-users and are for the reference of people who are writing code.

A bit more formally,  A comment is a description of a program about how it works in a simple readable format. These are usually used at places where some additional clarity needs to be provided to the developer who is reading through the code. Thus, thereby this helps in improving code readability and reduces time and communication that would be required for transferring knowledge.

/Interpreter simply ignores the comments in your code thereby not impacting the end output of your program. So in a nutshell comments are like a simple readable explanation for certain pieces of code.

Common Types of Comment

Most programming languages support 2 types of comments.

  • Single Line Comment
  • Multi-Line Comment / Block Comments

As the name suggests single-line comments are useful when one needs to add small single-line text eg. a particular condition, a constant value that needs a small description. Whereas multi-line work better when we have a larger amount of information to be added like a description about a function and how one can use it, etc.

There are some other types of comments like Document comments but that is out of the scope of this article.

Why should you add comments?

“Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler

The major advantage of adding comments is the enhanced readability and better understanding of the program. Apart from this, some other advantages include –

  • Comments make it super easy for your peers and even other developers to understand the logic without reading through long documentations.
  • Reduced communication between developers for small doubts
  • Comments are ignored by the compiler/interpreters.
  • For Open source software, these are a must since you won’t be there to explain every function to millions of developers who want to use that particular program.

Comments in Multiple Languages

Awesome, now that we learned about comments and why they are useful. Let’s explore how we can add comments in different programming languages.

Comments in C/C++

Single Line Comment

// This is a single line comment in C/C++

Multi-Line Comment

/* This is slightly longmulti line comment in C/C++ */

Comments in Python

Single Line Comment

# This is a single line comment in Python

Multi-Line Comment

# This is slightly long# multi line comment in Python

Comments in Java

Single Line Comment

// This is a single line comment in Java

Multi-Line Comment

/* This is slightly longmulti line comment in Java */

Comments in Ruby

Single Line Comment

# This is a single line comment in Ruby

Multi-Line Comment

=begin This is slightly longmulti line comment in Ruby=end

Comments in Golang

Single Line Comment

// This is a single line comment in Golang

Multi-Line Comment

/* This is slightly longmulti line comment in Golang */

Comments in Haskell

Single Line Comment

– – This is a single line comment in Haskell

Multi-Line Comment

{- This is slightly longmulti line comment in Haskell -}

Comments in Rust

Single Line Comment

// This is a single line comment in Rust

Multi-Line Comment

/* This is slightly longmulti line comment in Rust */

Comments in HTML

Single Line Comment

<!-- This is a single line comment in HTML -->

Multi-Line Comment

<!-- This is slightly longmulti line comment in HTML -->

Comments in CSS

Single Line Comment

/* This is a single line comment in CSS */

Multi-Line Comment

/* This is slightly longmulti line comment in CSS */

Comments in JavaScript

Single Line Comment

// This is a single line comment in Javascript

Multi-Line Comment

/* This is slightly longmulti line comment in Javascript */

Comments in R

Single Line Comment

# This is a single line comment in R programming language

Multi-Line Comment

R doesn’t support multi-line comments.

Comments in Erlang

Single Line Comment

% This is a single line comment in Erlang

Multi-Line Comment

R doesn’t support multi-line comments.

Comments in PHP

Single Line Comment

// This is a single line comment in PHP

Multi-Line Comment

/* This is slightly longmulti line comment in PHP */

Comments in Perl

Single Line Comment

# This is a single line comment in Perl

Multi-Line Comment

=begin This is slightly longmulti line comment in Perl=end

Comments in Kotlin

Single Line Comment

// This is a single line comment in Kotlin

Multi-Line Comment

/* This is slightly longmulti line comment in Kotlin */

Conclusion

The tutorial covered basics about comments and 2 common types – Single and Multi-line. I also tried to cover why are comments useful and one should write them when needed. I hope you learned something new!

Keep exploring. Keep learning! 👨‍💻