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C++ Fundamentals · Getting Started · Lesson 3 of 24

Comments and Structure

Concept

Comments and Structure

Two forward slashes start a single-line comment, and /* */ wraps a multi-line comment, both ignored by the compiler.

By the end of this lesson
  • Explain the core idea behind Comments and Structure.
  • Predict output before running a change.
  • Test one realistic and one unusual input.
  • Use the result to make the next decision.
How to study this page
  1. 1. Read one concept.
  2. 2. Change the example.
  3. 3. Run, compare, and explain.
  4. 4. Complete the challenge below.
ExampleRunnable
// This program greets the user
#include <iostream>
int main() {
    std::cout << "Welcome!"; // prints a greeting
    return 0;
}
Try it Yourself »
Self-check before continuing

Without looking at the example, describe what changes when you modify one input in Comments and Structure. Then reopen the editor and prove your explanation with a small test.

You are ready to continue when you can predict, test, and explain the result.

Your turn

Add a comment above one line explaining what it does.

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Console

Output will appear here...