C++ header files with no extension

Question

I am using an open source project (Open Scene Graph). I found that all the header file names are in File format, which I found to be File With No Extension

Answer 1

What I know is that most names were already taken by the C standard library. Since C++ has to co-exist with it, the C++ standard library may have evolved to not have an extension for its headers.

Note that these some of these headers may have the same name, but may or may not be similar in the functionality they offer.

#include //this includes the header C library
#include //this includes the header from the C++ standard library