C++ Multi-Line Comments

Multi-line comments in C++ are used to write comments that span across multiple lines. They are useful for detailed explanations, documentation blocks, or temporarily disabling large sections of code.

1. Syntax of Multi-Line Comments

In C++, multi-line comments start with /* and end with */. Everything written between these symbols is ignored by the compiler.

/*
   This is a multi-line comment.
   It can span multiple lines.
   The compiler ignores everything inside.
*/

#include <iostream>
using namespace std;

int main() {
    cout << "Hello, World!";
    return 0;
}

2. When to Use Multi-Line Comments

• To write detailed explanations about program logic.
• To describe functions or modules.
• To temporarily disable multiple lines of code.
• To add documentation at the top of a file.

3. Commenting Out a Block of Code

You can disable multiple lines of code using multi-line comments during debugging.

#include <iostream>
using namespace std;

int main() {
    int x = 10;

    /*
    int y = 20;
    cout << y;
    */

    cout << x;
    return 0;
}

4. File Header Documentation Example

/*
  Program Name: Simple Calculator
  Author: CodeCrown
  Description: This program performs basic arithmetic operations.
  Date: 18-02-2026
*/

#include <iostream>
using namespace std;

int main() {
    cout << "Calculator Program";
    return 0;
}

5. Important Notes

• Multi-line comments cannot be nested in C++.
• Make sure every /* has a matching */.
• Avoid using block comments to disable code that already contains block comments.

Conclusion

Multi-line comments in C++ are powerful tools for documentation and debugging. By using the /* */ syntax properly, developers can write cleaner, more maintainable, and well-documented programs.