C Programming Tutorial
About Lesson

C Comments

In this tutorial, we will learn about C comments, types of Comments, why we use them, and how to use them with the help of examples.


  • A well-documented program is a good practice as a programmer. It makes a program more readable and error finding became easier.
  • C comments are hints that a programmer can add to make their code easier to read and understand.
  • Comments are statements that are not executed by the compiler and interpreter.
  • Comments are One of the important part of good documentation.

Types of Comments

There are two ways to add comments to code:

1. Single Line Comments – //
2. Multi-line Comments – /* */

1. Single Line Comments

  • It is used to denote a single line comment.
  • In C, any line that starts with // is a Single-line comment.
  • It is referred to as C style comments as it is originally part of C Programming.

For example,

// declaring a variable
char a;

// initializing the variable 'a' with the value 2
a = 2;

Here, we have used two single-line comments:

  • // declaring a variable
  • // initializing the variable 'a' with the value 2

We can also use single line comment like this:

char a;    // declaring a variable

2. Multi-line comments

  • In C, any line between /* and */ is also a comment.
  • It is used to denote Multi-line Comment.
  • It can apply comment to more than a single line.

For example,

/* declaring a variable to store Name */
int salary = Algbly;

This syntax can be used to write both single-line and multi-line comments.

Using Comments for Debugging

Comments can also be used to disable code to prevent it from being executed. For example,

#include <stdio.h>
int main() {
    printf << "some code";
    printf << ''error code;
    printf  <<"some other code";
    return 0;
  • If we get an error while running the program, instead of removing the error-prone code, we can use comments to disable it from being executed;
  • this can be a valuable debugging tool.

Let’s see next example to use comments as debugging tool.

#include <stdio.h>
int main() {
    printf << "some code";
    // printf << ''error code;
    printf << "some other code";
    return 0;

Pro Tip: Remember the shortcut for using comments; it can be really helpful. For most code editors, it’s Ctrl + / for Windows and Cmd + / for Mac.

Why use Comments?

  • Comments can include a description of an algorithm to make code understandable.
  • If we write comments on our code, it will be easier for us to understand the code in the future.
  • Also, it will be easier for your fellow developers to understand the code.

Note: Comments shouldn’t be the substitute for a way to explain poorly written code in English. We should always write well-structured and self-explanatory code. And, then use comments.

As a general rule of thumb, use comments to explain Why you did something rather than How you did something, and you are good.

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