Will the following program cause any problem during compiling and execution process?
class A{
public: virtual void foo(){}
};
class B:public A{};
int main(){
B b;
b.foo();
}
views:
113answers:
4@Jon-Eric: I didn't do c++ development for several years and don't remember whether we should do something like `B b = new B()` in cpp?
Roman
2010-03-25 00:58:09
That was suprisingly easy to miss. Good catch!
spender
2010-03-25 01:00:18
@Roman: In general, you would only use `new` to create an object that needed to exist longer than the current scope. Otherwise, you would create the object on the stack as this question does. It saves you from having to destroy the object yourself, since that happens automatically at the end of the scope. More importantly, it prevents you from leaking memory if you forget to destroy the object, or if you throw an exception between your `new` and `delete`.
Josh Townzen
2010-03-25 01:58:42
A:
Why would it have a problem? You're calling a virtual function that IS defined on the parent class. B inherits it.
Alex
2010-03-25 00:57:09
+1
A:
Maybe, I'm guessing, they were testing if you knew the difference between virtual and abstract?
kervin
2010-03-25 00:59:08
+1
A:
There will be no problems compiling or running this program.
virtual functions can be overridden, but they don't have to be. If an object's class does not implement the virtual function, then the superclass will be checked for an implementation.
Paul
2010-03-25 01:34:04