Comments in C

A well-documented program is a good practice as a programmer. It makes a program more readable and error finding become easier. One important part of good documentation is Comments. 
 

  • In computer programming, a comment is a programmer-readable explanation or annotation in the source code of a computer program
  • Comments are statements that are not executed by the compiler and interpreter.

In C there are two types of comments : 

  1. Single line comment
  2. Multi line comment

Single line comments

Represented as // double forward slash. It is used to denote a single line comment. It applies comment to a single line only. It is referred to as C++-style comments as it is originally part of C++ programming. 

For example: 

// single line comment
// C program to illustrate
// use of single-line comment
#include <stdio.h>
int main(void)
{

	// Single line Welcome user comment
	printf("Welcome to GeeksforGeeks");
	return 0;
}

Output: 

Welcome to GeeksforGeeks

Multiline comments

Represented as /* any_text */ start with forward slash and asterisk (/*) and end with asterisk and forward slash (*/).  It is used to denote multi-line comment. It can apply comment to more than a single line. It is referred to as C-Style comment as it was introduced in C programming.

For example: 
 

/*Comment starts
continues
continues
.
.
.
Comment ends*/

Example: 

/* C program to illustrate
use of
multi-line comment */
#include <stdio.h>
int main(void)
{

	/* Multi-line Welcome user comment
	written to demonstrate comments
	in C/C++ */
	printf("Welcome to GeeksforGeeks");
	return 0;
}

Output: 

Welcome to GeeksforGeeks

Comment at End of Code Line

You can also create a comment that displays at the end of a line of code. But generally its a better practice to put the comment before the line of code.  

For example: 

 int age; // age of the person

When and Why to use Comments in programming?

  1. A person reading a large code will be bemused if comments are not provided about details of the program.
  2. Comments are a way to make a code more readable by providing more description.
  3. Comments can include a description of an algorithm to make code understandable.
  4. Comments can be helpful for one’s own self too if code is to be reused after a long gap.