who includes who?

Currently I am quite confused which file must include which one. (using Visual Studio)

If I have in my project just a single file anyname.h with content

Code:

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int main() { return 0; }

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[code tags are kinda useless for this very small part but I was forced to] then I can`t compile this. But if there is just a single file with anyname.cpp then it will compile. So I reasoned that the compiler just picks up any file and starts compiling.

If I have two files a.cpp and a.h it does not matter where is int main() { return 0; } and where is just int main();.

I think a good way to start is to create main.h and main.cpp. The first thing in main.cpp is #include main.h. But then? Where is best place to include stdlibs such as #include <iostream>? In main.h or main.cpp?

Also if I add other files such as myfunction.cpp and myfunction.h I have currently no clue who need to include who...

Can you recommend me anything to read what is the best way to structure this?

You don't put function definitions in headers. Especially not main().

A file includes exactly those headers it needs. If a.h needs something from <cstdlib> (for example, a type), it will include it. If only a.cpp needs something, that file will include it instead.

Where to put the definitions? No definitions at all?

In some tutorial I did read something like "Imagine you want to publish a dll for third party developers. All definitions go to the .h file, the implementations go into the .cpp file. Now you can publish your dll along with the header file and keep your source closed if wanted."

>> All definitions go to the .h file, the implementations go into the .cpp file.
That should read declarations (or possibly class definitions). Function definitions is what implementation is referring to among other stuff.

For main, there is no need to declare it in a header file at all. The reason is that you are not allowed to call main yourself, so no other piece of your code needs to see its declaration.

For other functions and classes, if you want to use them in multiple source (cpp) files, then you should declare them in a header. Otherwise it isn't necessary to declare them in a header then either.

Generally I might start with a main.cpp only (no main.h). If I need other files I create them as needed file1.h, file1.cpp, file2.h, file3.h, file3.cpp, etc. Except for your main.cpp, almost all your cpp files will correspond to a header file.

- All function prototypes and class definitions go into headers.
- All class and function templates go into headers (there may be exceptions, but this is the general way it's done).
- All header files should include the other headers it needs to work properly (so if a class definition uses another class, it should include that class definition header).
- All implementation and function definitions go into source files.
- Source files include appropriate header files to see the declarations and class definitions (and template classes/functions).
- Source files include appropriate headers like cstdlib when they need them.

That's about how it works.
Headers ends with .h (the most common I think) or .hpp.
All source files ends with .c (for C) and .cpp (for C++).

Quote:

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so if a class definition uses another class, it should include that class definition header

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if class includes (or function parameter is) pointer or reference to another class - no need to include file with the full class definition, enough to have a forward declaration to avoid unneded header dependencies.

full heder of the referenced class will be included in source file where the class is actually accessed