title: Abstract base class implementation
body: <p>Here is an interview question :</p>
  
  <p>How can we implement an <strong>abstract base class</strong> without using <strong>pure virtual functions</strong>.
   What we can do so that we cannot create any <strong>object</strong> of a class because in that case we can say our class is an <strong>abstract base class.</strong></p>
  
  <p>At first I thought of using an <strong>virtual destructor</strong> but I am not sure about this solution because of virtual keyword. Can you please help?</p>