polymorphism

[subramanian]

Consider the program:

#include <iostream>
#include <string>

class A {
public:
virtual void print(void) const;
};

void A:rint(void) const
{
std::cout << "A:rint()\n";
return;
}

class B : public A {
public:
void print(void) const;
};

void B:rint(void) const
{
std::cout << "B:rint()\n";
return;
}

class C : public B {
public:
void print(void) const;
};

void C:rint(void) const
{
std::cout << "C:rint()\n";
return;
}

int main(void)
{
C c;
A *pa = &c;
pa->print();

return 0;
}

If I run this program the output is:
C:rint()

Question:
A:rint() is declared virtual. Since B:rint()const is not virtual,
how does pa->print() calls C:rint() ?

 

[red floyd]

Consider the program:

#include <iostream>
#include <string>

class A {
public:
virtual void print(void) const;
};

void A:rint(void) const
{
std::cout << "A:rint()\n";
return;
}

class B : public A {
public:
void print(void) const;
};

void B:rint(void) const
{
std::cout << "B:rint()\n";
return;
}

class C : public B {
public:
void print(void) const;
};

void C:rint(void) const
{
std::cout << "C:rint()\n";
return;
}

int main(void)
{
C c;
A *pa = &c;
pa->print();

return 0;
}

If I run this program the output is:
C:rint()

Question:
A:rint() is declared virtual. Since B:rint()const is not virtual,
how does pa->print() calls C:rint() ?

You're proceeding from a faulty assumption. If a method is virtual in
the base, it's virtual in all the derived classes. B:rint() const
*IS* virtual.