title: C++: Where to write the code documentation: in .cpp or in .hpp files?
body: <p>Where is it customary to write the in-code documentation of classes and methods?    </p>
  
  <p>Do you write such doc-blocks above the corresponding class/method in the header (.hpp) file, or within the source (.cpp) file?  </p>
  
  <p>Is there a widely respected convention for such things? Do most C++ projects do it one way rather than the other?  </p>
  
  <p>Or should documentation be written on the two sides (i.e. in the .hpp and the .cpp files), maybe with one short description one one side and a longer one on the other side?  </p>
  
  <p>Most importantly, are there any practical considerations that makes it more convenient to write it one way rather than the other way ? (E.g. the use of automatic documentation parsers and generators like Doxygen...) </p>