title: Is C NULL equal to C++11 nullptr
body: <p>I like to use <code>nullptr</code> instead of NULL. Now I call a C function (from <code>libjansson</code> in this case).</p>
  
  <p><code>NULL</code> in C is implementation <a href="http://en.cppreference.com/w/c/types/NULL" rel="noreferrer">defined</a>.</p>
  
  <p>For <code>nullptr</code> I found that "A null pointer constant is an integral constant expression (5.19) rvalue of integer type that evaluates to zero".</p>
  
  <p>So the safest thing to do:</p>
  
  <pre><code>auto string_obj=json_object_get(m_handle,name);
  if(string_obj!=NULL)
      {
      auto string=json_string_value(string_obj);
      if(string!=NULL)
          {return string;}
      }
  return nullptr;
  </code></pre>
  
  <p>Do I really need that or can I do it simpler:</p>
  
  <pre><code>auto string_obj=json_object_get(m_handle,name);
  if(string_obj!=nullptr)
      {
      return json_string_value(string_obj); //Assume there is no difference between C NULL and C++11 nullptr
      }
  return nullptr;
  </code></pre>