Comments

A comment is a piece of text within a program that is not executed. It can be used to provide additional information to aid in understanding the code.

Single-line Comments

Single-line comments are created using two consecutive forward slashes. The compiler ignores any text after // on the same line.

// This line will denote a comment in C

Multi-line Comments

Multi-line comments are created using /* to begin the comment, and */ to end the comment. The compiler ignores any text in between.

/*
This is all commented out.
None of it is going to run!
*/

Header Comment

Multi-line comments can be used to create a header comment at the top of the file. File header comments are used to identify the author of the code, the date the code was written, a description of the program, etc. This is a common convention in the C language.

/***************************************************************
* FILENAME: hello.c
* DESCRIPTION: This program prints a message to the screen.
* AUTHOR: Gilfoyle
* DATE: 04/20/2023
* MODIFICATION: Dinesh
* CHANGES: N/A
****************************************************************/

Example

Here’s a program with a multi-line comment and three single-line comments:

/* Tip Calculator
Written by Sonny */

#include <stdio.h>

int main() {
  // Calculate the tip
  double total = 18.75;
  double tip = total * 0.2;

  // Display the tip
  printf("The tip is $%.2f\n", tip); // Show two decimal places

  return 0;
}