title: how do i include multiple class with the same includes?
body: <p>How do i include two .h/class files that both have <code>#include "h_file.h"</code>? both require the .h file definitions, and both are included in the main program. how do i prevent the redefinition of the .h definitions (which causes the compiler to not compile)?</p>
  
  <p>i have:</p>
  
  <pre><code>main.cpp
  class1.h/class1.cpp
  class2.h/class2.cpp
  h_file.h
  </code></pre>