C++ Comments

Welcome to The Coding College! Comments are an essential part of programming, allowing you to explain your code, document logic, and improve readability. In this tutorial, we’ll cover everything you need to know about C++ comments, from their types to best practices.

What Are Comments in C++?

In C++, comments are lines of text ignored by the compiler. They are used for:

  • Explaining code logic.
  • Adding notes for future reference.
  • Collaborating effectively in teams.

Comments do not affect the execution of the program.

Types of Comments in C++

C++ supports two types of comments:

  1. Single-line comments
  2. Multi-line comments

1. Single-line Comments

Single-line comments start with two forward slashes (//). The compiler ignores everything after // on that line.

Example:

#include <iostream>  

int main() {  
    int age = 25;  // Declares an integer variable named 'age'  
    std::cout << "Age: " << age << std::endl;  // Prints the value of 'age'  
    return 0;  
}

Output:

Age: 25

2. Multi-line Comments

Multi-line comments start with /* and end with */. Everything between these markers is ignored by the compiler.

Example:

#include <iostream>  

int main() {  
    /*  
    This is a multi-line comment.  
    It can span multiple lines.  
    */  
    std::cout << "Welcome to The Coding College!" << std::endl;  
    return 0;  
}

Output:

Welcome to The Coding College!

Where to Use Comments

  • Documenting Variables and Functions 
int age = 25;  // Stores the user's age
  • Explaining Complex Logic 
// Check if the number is even  
if (number % 2 == 0) {  
    std::cout << "The number is even." << std::endl;  
}
  • Disabling Code Temporarily 
// std::cout << "This line is commented out and won't execute." << std::endl;
  • Adding File or Function Documentation 
/*  
This program calculates the area of a rectangle.  
Author: John Doe  
Date: Dec 14, 2024  
*/

Best Practices for Writing Comments

  • Keep Comments Relevant and Concise
    Avoid redundant comments. Let your code and comments complement each other. 
int x = 10;  // Good: Assigns the value 10 to 'x'  
// int x = 10; Assigns the value 10 to 'x'  // Bad: Repeats the code meaning
  • Use Comments to Explain Why, Not What
    Focus on explaining the purpose of the code rather than repeating what it does. 
// Calculate the final price after applying a discount  
totalPrice = price - (price * discount);
  • Avoid Overusing Comments
    If your code is simple and self-explanatory, comments may not be necessary.
  • Maintain Consistent Style
    Use a consistent format for comments throughout your program.
  • Update Comments
    Ensure your comments remain accurate as you modify your code.

Comments vs. Code Readability

While comments are helpful, strive to write clean and self-explanatory code. For example:

  • Use descriptive variable names (totalPrice instead of tp).
  • Organize your code logically with proper indentation.

Learn More with The Coding College

At The Coding College, we emphasize writing clean, well-documented code. Explore our tutorials for more tips on improving your coding practices and mastering C++.

What’s Next?

  1. Practice using comments in your C++ programs.
  2. Learn about advanced concepts like documentation generators (e.g., Doxygen).

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