title: C++ including from the other directory doesn't work
body: <p>Yes, I know there's like 100000000 questions like this on this site. I spent 2 hours lurking SO to find out what am I doing wrong. This is my projects directory tree:</p>
  
  <p><a href="https://i.stack.imgur.com/OMnrM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OMnrM.png" alt="enter image description here"></a></p>
  
  <p><code>main.cpp</code> starts with this:</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include "XD.hpp"
  </code></pre>
  
  <p>(<code>lib/XD.hpp</code> or <code>&lt;XD&gt;</code> doesn't work as well)</p>
  
  <p>I tried many other combination, I even did <code>-I/home/frynio/Desktop/projects/sdizo1/lib</code>, but it still doesn't work. Do you guys see what am I doing wrong here?</p>
  
  <p>I know this will be massively downvoted, but I'd rather spend time working on my project rather than trying to figure out this thing.</p>