title: Makefile with multiple source folders
body: <p>I'm trying to write a make file for my C++ project</p>
  
  <p>I have the following source structure</p>
  
  <p>project folder content:</p>
  
  <pre><code>main.cpp
  lib/
  include/
  src/
  </code></pre>
  
  <p>as the name says 'main.cpp' contain the main() function, include hold the *.h files and src hold *.cpp file (and in case other subfolders with other sources)</p>
  
  <p>what I would like to achieve is a makefile that as target compile main.cpp and all his included sources recursivelly , without specify all the sources names or mantaining the make file adding a source every time I create or add it</p>
  
  <p>any help or a good tutorial to solve this problem would be very appreciated</p>