title: C++: Reason why using ".hh" as extension for C++ header files
body: <p>I would like to know why we use ".hh" as extension for C++ header files instead of using just ".h".</p>
  
  <p>The header files are preprocessed and the preprocessor doesn't even care about the extension of the header file. So, even if I create a header file with an extension ".qwe" (test.qwe). Then, why to use ".hh" as extension for C++ header files. </p>
  
  <p>Some say, we are using ".cc" as extension for C++ files to differentiate from C files (which has an extension ".c"), likewise we are using using ".hh" as extension for C++ header files to differentiate from C header files (which has an extension ".h"). I don't think this to be a valid reason.</p>
  
  <p>Does anyone know the reason for naming in such a way?</p>