Functions

returnType name(parameters) {
    // code
    return value;
}

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

void greet(string name = "friend") {   // void returns nothing
    cout << "Hello, " << name << endl;
}

int main() {
    cout << square(5) << endl;
    greet();
    greet("Sara");
}