// Fig. 19.4: fig19_04.cpp // Casting base-class pointers to derived-class pointers #include using std::cout; using std::endl; #include #include "point.h" #include "circle.h" int main() { Point *pointPtr = 0, p( 30, 50 ); Circle *circlePtr = 0, c( 2.7, 120, 89 ); cout << "Point p: " << p << "\nCircle c: " << c << '\n'; // Treat a Circle as a Point (see only the base class part) pointPtr = &c; // assign address of Circle to pointPtr cout << "\nCircle c (via *pointPtr): " << *pointPtr << '\n'; // Treat a Circle as a Circle (with some casting) // cast base-class pointer to derived-class pointer circlePtr = static_cast< Circle * >( pointPtr ); cout << "\nCircle c (via *circlePtr):\n" << *circlePtr << "\nArea of c (via circlePtr): " << circlePtr->area() << '\n'; // DANGEROUS: Treat a Point as a Circle pointPtr = &p; // assign address of Point to pointPtr // cast base-class pointer to derived-class pointer circlePtr = static_cast< Circle * >( pointPtr ); cout << "\nPoint p (via *circlePtr):\n" << *circlePtr << "\nArea of object circlePtr points to: " << circlePtr->area() << endl; return 0; } // end function main /************************************************************************** * (C) Copyright 1992-2004 by Deitel & Associates, Inc. and * * Pearson Education, Inc. All Rights Reserved. * * * * DISCLAIMER: The authors and publisher of this book have used their * * best efforts in preparing the book. These efforts include the * * development, research, and testing of the theories and programs * * to determine their effectiveness. The authors and publisher make * * no warranty of any kind, expressed or implied, with regard to these * * programs or to the documentation contained in these books. The authors * * and publisher shall not be liable in any event for incidental or * * consequential damages in connection with, or arising out of, the * * furnishing, performance, or use of these programs. * *************************************************************************/