title: One header for multiple cpp-files
body: <p>Let's assume I have 3 cpp-files:</p>
  
  <pre><code>Main.cpp
  First.cpp
  Second.cpp
  </code></pre>
  
  <p>Now i want to use functions from First and Second in Main. Is there something to complain about, if I used only one header-file for both cpp-files and their functions?</p>
  
  <p>Could there be any problems, when using the header-file in First, because I need a Function from Second in First?</p>