Summary - Functions

Combine overloading and default parameters to write a math helper class.

Summary: Functions

In this group you learned C++ functions. The definition void greet() { ... } creates a function; the call greet(); runs it. The signature is return type + name + parameter list.

Functions that return a value send a result back with return; void only performs a side effect. Parameters are copied by value. Sharing a name with different parameters is overloading; giving parameters a default value is the default parameter feature. These are the foundations of breaking code into reusable pieces.

Exercise Write a square function

Define an int square(int x) function that returns x * x. In main, call square(7) and print the result.

Show example solution

#include <iostream>

int square(int x) {
    return x * x;
}

int main() {
    std::cout << square(7) << std::endl;
    return 0;
}

Exercise Sum with overloads

Define two add overloads: int add(int a, int b) and double add(double a, double b). In main, call both and print the results separated by a space.

Show example solution

#include <iostream>

int add(int a, int b) {
    return a + b;
}

double add(double a, double b) {
    return a + b;
}

int main() {
    std::cout << add(2, 3) << " " << add(2.5, 3.5) << std::endl;
    return 0;
}

Test yourself

Which of the following is a valid function signature?
```
// ???
```
- greet
- void greet
- void greet()
- greet();
Show answer

void greet() — return type + name + parameter list is the full signature.
Match the concepts

return

Returns a value
void

Returns nothing
overloading

Same name, different parameters
b = 0

Default value

Complete the call

std::cout << add(____, 4) << std::endl;

Show answer

std::cout << add(3, 4) << std::endl;

Next lesson: What is a reference?

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