Pros & Cons of putting all code in Header files in C++?

Question

You can structure a C++ program so that (almost) all the code resides in Header files. It essentially looks like a C# or Java program. However, you do need at least one

Answer 1

Well, as many have pointed out there is a lot of cons to this idea, but to balance out a bit and provide a pro, I would say that having some library code entirely in headers makes sense, since it will make it independent of other settings in the project it is used in.

For example, if one is trying to make use of different Open Source libraries they can be set to use different approaches for linking to your program - some may use the operating system's dynamically loaded library code, others is set to be statically linked; some may be set to use multithreading, while others is not. And it may very well be an overwhelming task for a programmer - especially with a time constraint - to try to sort these incompatible approches out.

All of that is however not an issue when using libraries that are contained entirely in headers. "It just works" for a reasonable well-written library.