FAQ: Functions: Scope & Flexibility - Multi-File Programs

This community-built FAQ covers the “Multi-File Programs” exercise from the lesson “Functions: Scope & Flexibility”.

Paths and Courses
This exercise can be found in the following Codecademy content:

Learn C++

FAQs on the exercise Multi-File Programs

There are currently no frequently asked questions associated with this exercise – that’s where you come in! You can contribute to this section by offering your own questions, answers, or clarifications on this exercise. Ask or answer a question by clicking reply (reply) below.

If you’ve had an “aha” moment about the concepts, formatting, syntax, or anything else with this exercise, consider sharing those insights! Teaching others and answering their questions is one of the best ways to learn and stay sharp.

Join the Discussion. Help a fellow learner on their journey.

Ask or answer a question about this exercise by clicking reply (reply) below!
You can also find further discussion and get answers to your questions over in #get-help.

Agree with a comment or answer? Like (like) to up-vote the contribution!

Need broader help or resources? Head to #get-help and #community:tips-and-resources. If you are wanting feedback or inspiration for a project, check out #project.

Looking for motivation to keep learning? Join our wider discussions in #community

Learn more about how to use this guide.

Found a bug? Report it online, or post in #community:Codecademy-Bug-Reporting

Have a question about your account or billing? Reach out to our customer support team!

None of the above? Find out where to ask other questions here!

Why do we need to declare the functions above main in the main cpp file in the first place?
I assume the system wouldn’t actually look for the functions in other files unless we declare them above main?

simple enough to find out:

#include <iostream>

int main() {



// Definition at the bottom:
void eat() {

  std::cout << "nom nom nom\n";


as you can see, i removed the declaration at the top, now the program gives an error. This is because you use the function before its declared.

Yeah Well was wondering if we could just call it without actually declaring it at all ( since we declare and define it in the other file) … gave it a few tests and faced fatal errors. see why now.

why i can’t compile although i did same the hint

Because your code contains syntax errors? You declare functions, but the function don’t seem to have a body/purpose.

Did you defined the functions in the other file named “my_functions.cpp” ??

But why do we need to declare them after all ?? Don’t the compiler automatically know that the functions exist in the other file ?

thankfully not, once you have several hundred files or maybe thousand files, you don’t want to load the files/functions you don’t need. Which is why we import them manually.

1 Like

Really helpful :innocent: Thank you ! @stetim94