In what order should headers be included?

Question

What order should headers be declared in a header / cpp file? Obviously those that are required by subsequent headers should be earlier and class specific headers should be in cpp scope not header scope, but is there a set order convention / best practice?

Answer 1

In a header file you have to include ALL the headers to make it compilable. And don't forget to use forward declarations instead of some headers.

In a source file:

• corresponded header file
• necessary project headers
• 3rd party libraries headers
• standard libraries headers
• system headers

In that order you will not miss any of your header files that forgot to include libraries by their own.