I’m trying to separate functions from main.cpp to make a better overview in the project. The idea is to place these functions in another .cpp file (called functions.cpp or something) and include this file in main.cpp.
I tried using #include “functions.cpp”, but only received Error 1
Does anyone have a good solution?
My skills are very basic 
This is a basic concept of object-oriented programming and should be near the beginning of whatever C++ curriculum you are studying. I haven’t touched C++ since high school, so I wouldn’t want to lead you astray with my expectations about how importing works in Python and JavaScript. However, there are some knowledgeable people on the Internet and some quick searching can find where they have provided this information in the past. That first post contains the information you want to know.