36. Safer casting with dynamic_cast

• Use dynamic_cast when you are converting up or down a type hierarchy and want runtime checking:

  
      Derived* dp;
  
      // Trust the compiler:
      Base* bp = dynamic_cast< Base* >( dp ); // surely safe
  
      Derived* dp = dynamic_cast< Derived* >( bp );
  
      if ( dp != NULL ) {
          // cast worked fine:
          //...
      } else {
          // *bp wasn't really a Derived object!!
          //...
  
  

• dynamic_cast is an operator that requires a polymorphic operand.

• It comes with a small run-time cost overhead.

• Safe and portable.