title: Should I still use #include guards AND #pragma once?
body: <p><img src="https://i.stack.imgur.com/IrEGu.png" alt="enter image description here"></p>
  
  <p><a href="http://en.wikipedia.org/wiki/Pragma_once">http://en.wikipedia.org/wiki/Pragma_once</a><br>
  Should I still use include guards when all of these compilers support <code>#pragma once</code>?<br>
  A lot of responses on stack overflow say to use both for compatibility, but I'm not sure if that still rings true.
  What compilers today don't support <code>#pragma once</code>?  </p>
  
  <p>I am not sure if using both was just a recommendation before it became widley adopted, or if there are still very good reasons to use both methods.<br>
  Any examples of when only using <code>#pragma once</code> will cause problems?</p>