Go4Expert - Overrding virtual methods

Go4Expert (http://www.go4expert.com/)

- C++ (http://www.go4expert.com/forumdisplay.php?f=100)

- - Overrding virtual methods (http://www.go4expert.com/showthread.php?t=19268)

Overrding virtual methods

Hi,

I've defined an abstract class IBase with a single method

virtual bool foo(){ printf(" IBase \n"); }

I've also defined a derived class TestDerived:IBase that overrides this method

bool foo(){ printf(" TestDerived \n");}

Finally I've a static lib with a function to use a IBase class

bool doSomething(IBase * foo);

implemented inside the library :

bool doSomething(IBase * foo){ foo->foo(); }

And this is the main program :
#include "mystaticlib.h"

int main(){
IBase * ptr = new TestDerived();
ptr->foo();
doSomething(ptr);
}
I was especting an output like :

TestDerived
TestDerived

But the output is

TestDerived
IBase

Why inside the lib, the ptr is accessing to the method of the base?

Thanks in advance.

Re: Overrding virtual methods

Hi,

Here is the program you have explained below and it's output too

Code:

#include<iostream.h>



class Base

{

  public:

    virtual bool foo()

    {

      cout<<"Base::foo"<<endl;

    }

};

  

class Derived: public Base

{

  public:

    bool foo()

    {

      cout<<"Derived::foo"<<endl;

    }

};



bool doSomething(Base * foo)

{ 

  foo->foo(); 

}



int main()

{

  Base *bptr = new Derived();

  bptr->foo();

  doSomething(bptr);

  

  return(0);

}

output:

Derived::foo
Derived::foo

You must get the output as you were expecting. I think, you have made some mistake to get the output as

Derived::foo
Base::foo

So, double check your code.

Re: Overrding virtual methods

I double check it ..... and you were right. :) The output is ok.

Thanks for all.