small confusion about the the C++ programming language by B.S.

[puzzlecracker]

on page 312 of 3ed SE edition last paragraph:
=======
.......
Calling a function using scope resolution operator:: as is done in
Manager:rint()ensures that the virtual mechanism is not used.
Otherwise, Manager:rint() would suffer an infinite recursion.\
....
...
==================
My question is WHY would you have an infinite recursion if,
hypothtically speaking, virtual mechanism were to be used?

 

[Victor Bazarov]

on page 312 of 3ed SE edition last paragraph:
=======
......
Calling a function using scope resolution operator:: as is done in
Manager:rint()ensures that the virtual mechanism is not used.
Otherwise, Manager:rint() would suffer an infinite recursion.\
...
..
==================
My question is WHY would you have an infinite recursion if,
hypothtically speaking, virtual mechanism were to be used?

It would keep calling itself, most likely (I don't have the book
handy).

V

 

[puzzlecracker]

i still a bit confusing.

 

[puzzlecracker]

i still a bit confusing.

 

[ES Kim]

on page 312 of 3ed SE edition last paragraph:
=======
......
Calling a function using scope resolution operator:: as is done in
Manager:rint()ensures that the virtual mechanism is not used.
Otherwise, Manager:rint() would suffer an infinite recursion.\
...
..
==================
My question is WHY would you have an infinite recursion if,
hypothtically speaking, virtual mechanism were to be used?

Think over what the following code would do if it were not for ::.

void Manager:rint() const
{
print(); // meaning this->print();
}

 

[David White]

i still a bit confusing.

If the virtual mechanism were used every time, the same function would be
called every time (Manager:rint), because that's the correct function for
the type of object. Therefore the call to Employee:rint from inside
Manager:rint cannot use the virtual mechanism. If it did, Manager:rint
would call itself instead of Employee:rint.

DW

 

[puzzlecracker]

If the virtual mechanism were used every time, the same function would be
called every time (Manager:rint), because that's the correct function for
the type of object. Therefore the call to Employee:rint from inside
Manager:rint cannot use the virtual mechanism. If it did, Manager:rint
would call itself instead of Employee:rint.

DW

THANKS

it is so trivial; should read carifully next time...



I thought of something like that:

Derived D*=new Derived();
D->Base:rint();

anyway, thx again