title: how to call derived function using base class object
body: <pre><code>class Parent
  {
      public int GetNo()
      {
          return 1;
      }
  }
  
  class Child : Parent
  {        
      public Child()
      {
  
      }
  
      public int GetNo()
      {                       
          return 2;
      }
  }
  
  Parent p = new Child();
  p.GetNo();
  </code></pre>
  
  <p>But it calls <code>Base.GetNo()</code>. I know if I use virutal in base it will call <code>Child.GetNo()</code>
  But i can't use virutal in Base becuase i have to derive my class from base which is already distributed in DLL.So there's no way i can modify the existing functions of base class.</p>
  
  <p>Any sugguestions are valued.
  Thanks</p>