functions.cpp

int main() {
    // So this is my main function
    // it gets called automatically, but otherwise its no different then any other function
    
    int number_of_tates = 0; // I take inspiration from my enviroment ;)
    
    number_of_tates = work_on_song(number_of_tates); // Now I'm going to call my function, which I define down below.
                                                     // It takes an integer, the old amount, and returns an integer (the new amount).
                                                     // After calling the function, I assign it to the variable "number_of_tates",
                                                     // overwriting the old value.
    cout << number_of_tates << end; // prints '3'
    
    number_of_tates = work_on_song(number_of_tates); // Now I can call the same function again
    number_of_tates = work_on_song(number_of_tates); // and again
    number_of_tates = work_on_song(number_of_tates); // without rewriting the same code.
    
    cout << number_of_tates << end; // prints '12'
}

int work_on_song(int n) { // How to parse this: 
                          // returnType function_name(argumentType argumentVariableName [And then possibly more arguments after that])
                          // How to say it:
                          // Function work_on_song takes an integer (named n) and returns an integer.
                          
    return n + 3; // This could potentially be a much more complicated piece of code (that you'd want to test by itself for example,
                  // before integrating into a much bigger system).
                  // This way, you can keep your code clean, seperate and modular.
}

// To be exceedingly pedantic, this code won't compile as is. Because of historical reasons, 
// C++ functions need to be declared above where you want to use them.