How Can I Properly Organize Header Files in C++?

You might want to consider splitting your classes if you have heavy dependencies. For instance, instead of including everything in your header, you can forward declare types and isolate your implementation. Here's a quick peek at how you could handle it:

```cpp
// Header file
typedef struct type; // Forward declare your type here.

class C {
friend class C_impl;
C();
public:
type interface();
};
```

In your source file, handle the actual implementation. This way, client code won't need to know about all the implementation details unless necessary. It’s a great way to keep things clean and manage dependencies better.

It's definitely worth addressing this early on! One good approach is the Pimpl (Pointer to Implementation) idiom. It lets you hide your implementation details behind a pointer to an incomplete type, which helps keep your headers cleaner. Only include necessary headers in your .cpp files instead of headers, reducing unnecessary dependencies.

You could also create a single public header for each module that only exposes what's necessary, while keeping internal implementations in separate headers that aren't included elsewhere.