title: Is lowercase null valid in C++?
body: <p>Is there any lowercase <code>null</code> in any version of C++ language specification?</p>
  
  <h3>Background:</h3>
  
  <p>I was asked in an interview "Which of the following pointer initializations are valid?", and I filled the form something like:</p>
  
  <pre><code>// valid
      int* p1 = 0;
      int* p2 = 2-2;
      int* p6 = new int;
  // invalid
      int* p3 = 1; 
  
      int z = 0;
      int* p4 = z;
  // ???
      int* p5 = null;
  </code></pre>