RivoCode

C++ Fundamentals · Functions · Lesson 13 of 24

Declaring Functions

Concept

Declaring Functions

A function has a return type, a name, and parameters. void means it returns nothing.

By the end of this lesson
  • Explain the core idea behind Declaring Functions.
  • 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
int add(int a, int b) {
    return a + b;
}
int main() {
    std::cout << add(3, 4);
}
Try it Yourself »
Self-check before continuing

Without looking at the example, describe what changes when you modify one input in Declaring Functions. 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

Write a function square(int n) that returns n multiplied by itself.

Loading editor…

Console

Output will appear here...