title: #include "date.h" creates error E1696 cannot open source file "date.h", and also cannot open include file: No such file or directory
body: <p>The code was intended to cout the day of week.
  Using Visual Studio 2017 and the version is 15.8.280 10.2050</p>
  
  <p>Code was copied from here: <a href="https://howardhinnant.github.io/date/date.html" rel="nofollow noreferrer">https://howardhinnant.github.io/date/date.html</a></p>
  
  <p>The code didn't run and showed the errors mentioned already and also that Name must be a namespace name and "weekday" is undefined. </p>
  
  <p>My skills are minimal at this point. Just starting to understand what things are called and sort of how they fit together. </p>
  
  <p>Also, what are the things that are after #include called? some are header files right? but what about the others like fstream etc. ?</p>
  
  <p>Thanks! </p>
  
  <p>Many searches online found no answer directly. There were some related but nothing that explained it in a way i could understand. </p>
  
  <pre><code>#include "date.h"
  #include &lt;iostream&gt;
  
  int
  main()
  {
      using namespace date;
      std::cout &lt;&lt; weekday{ August / 22 / 2019 } &lt;&lt; '\n';
  }
  </code></pre>