title: How do I check for C++20 support? What is the value of __cplusplus for C++20?
body: <p>Related to questions <a href="https://stackoverflow.com/questions/5047971/how-do-i-check-for-c11-support">How do I check for C++11 support?</a> and <a href="https://stackoverflow.com/questions/38456127/what-is-the-value-of-cplusplus-for-c17">What is the value of __cplusplus for C++17?</a></p>
  
  <p>How can I inquire whether the compiler can handle / is set up to use C++20? I know that it is, in principle, possible to inquire the C++ version by:</p>
  
  <pre><code>#if __cplusplus &gt; ???
    // C++20 code here
  #endif
  </code></pre>
  
  <p>What should <code>???</code> be for C++20?</p>