Inherited pointer problem
Author
Hi
Using c++ and mvc++ 2005 i have a unit class and inherited from it a have ship and aircraft class like so
class aircraft:public unit
Now, my player has a (unit * theUnit) to keep track of the currently controlled unit, which can be both ship and aircrafts. But if i wanna get hold of the ship-specific data from this pointer doing this:
ship * s=(ship *)theUnit;
It compiles fine, but the ship-data s points to is corrupted, while the unit-specific data s points to is the real stuff. How to solve this?
Thanks
Erik
That sounds like a slicing problem.
How exactly do you create the new object and assign the pointer?
Make sure you do work with pointers, you can't do that with a "true" (as in non pointed to) object.
@SiCrane: Thanks for correcting, i had written shearing instead of slicing.
[Edited by - Endurion on March 7, 2008 11:42:21 AM]
How exactly do you create the new object and assign the pointer?
Make sure you do work with pointers, you can't do that with a "true" (as in non pointed to) object.
@SiCrane: Thanks for correcting, i had written shearing instead of slicing.
[Edited by - Endurion on March 7, 2008 11:42:21 AM]
I think you mean slicing problem. Alternately, it could just be the case that you're casting a pointer to an object that isn't actually a Ship to a Ship pointer.
Quote:Original post by suliman
Now, my player has a (unit * theUnit) to keep track of the currently controlled unit, which can be both ship and aircrafts. But if i wanna get hold of the ship-specific data from this pointer doing this:
ship * s=(ship *)theUnit;
A good way out of this would be to refactor your code so that all the data needed is provided by the unit base-class, or by polymorphic functions declared in the base-class.
Also, if you replace your casting code with
it might be easier to test what SiCrane said. Dynamic casting is "safer" because if the cast fails (because theUnit is not actually pointing to a ship), s will be a null-pointer, which you can check for.
ship* s = dynamic_cast<ship*>(theUnit);it might be easier to test what SiCrane said. Dynamic casting is "safer" because if the cast fails (because theUnit is not actually pointing to a ship), s will be a null-pointer, which you can check for.
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement