C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Having a pointer to a parent class ?          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Gabriel Leblanc Guest Posted: Sun Mar 07, 2004 7:16 pm    Post subject: Having a pointer to a parent class ? Is it possible to have a pointer that works like this ? class ship Quote: ----------------- | | class cruiser class destroyer : public ship : public ship ///////// ship* selectedShip; if(buttonPressed = 1) selectedShip = &cruiser1 //Say, have a pointer to an instance of a cruiser else selectedShip = &destroyer1 //Say, have a pointer to an instance of a destroyer Thanks ! Back to top Mike Wahler Guest Posted: Sun Mar 07, 2004 7:45 pm    Post subject: Re: Having a pointer to a parent class ? "Gabriel Leblanc" <gabriel.leblanc (AT) a2m (DOT) com> wrote Quote: Is it possible to have a pointer that works like this ? class ship | | ----------------- | | | | class cruiser class destroyer : public ship : public ship ///////// ship* selectedShip; if(buttonPressed = 1) selectedShip = &cruiser1 //Say, have a pointer to an instance of a cruiser else selectedShip = &destroyer1 //Say, have a pointer to an instance of a destroyer Thanks ! Sure. What have you tried? Example: #include <iostream> class Ship { public: virtual void what_am_I() const = 0; }; class Cruiser : public Ship { public: void what_am_I() const { std::cout << "I am a Cruisern"; } }; class Destroyer : public Ship { public: void what_am_I() const { std::cout << "I am a Destroyern"; } }; void foo(const Ship *p) { p->what_am_I(); } int main() { Cruiser c; Destroyer d; foo(&c); /* prints "I am a Cruiser" */ foo(&d); /* prints "I am a Destroyer" */ return 0; } Which C++ book(s) are you reading? -Mike Back to top Daniel T. Guest Posted: Sun Mar 07, 2004 8:10 pm    Post subject: Re: Having a pointer to a parent class ? [email]gabriel.leblanc (AT) a2m (DOT) com[/email] (Gabriel Leblanc) wrote: Quote: Is it possible to have a pointer that works like this ? class ship | | ----------------- | | | | class cruiser class destroyer : public ship : public ship ///////// ship* selectedShip; if(buttonPressed = 1) selectedShip = &cruiser1 //Say, have a pointer to an instance of a cruiser else selectedShip = &destroyer1 //Say, have a pointer to an instance of a destroyer How do you *know* that the selectedShip is a cruiser or destroyer? Assuming you have at least one virtual function in ship, something like this would do what you want... ship* selectedShip; if ( buttonPressed == 1 ) // note the double '=' { cruiser* cruiser1 = dynamic_cast<cruiser*>(selectedShip); assert( cruiser1 ); // do stuff with cruiser1 } else { destroyer* destroyer1 = dynamic_cast<destroyer*>(selectedShip); assert( destroyer1 ); // do stuff with destroyer1 } But I wouldn't recommend such code. Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.