title: Passing NULL to enum type input parameter - C++
body: <p>In my code, I have two enums like below:</p>
  
  <pre><code>enum myEnum{e1, e2};
  enum myEnum2{e3, e4};
  </code></pre>
  
  <p>I have a function prototype like below:</p>
  
  <pre><code>void function myFunc(myEnum in_enum1, myEnum in_enum2){
  
      some-code-here;
  
  }
  </code></pre>
  
  <p>In some condition, I have to leave empty the second input parameter in_enum2.</p>
  
  <p>I tried passing NULL to it, but compiler gave parameter initialization error when doing so.</p>
  
  <p>How can I pass NULL to an enum type input parameter?</p>
  
  <p>Thanks in advance.</p>