Overrided Function Causing Problems

[sbvishal]

Dear All
I am writing a sample code which is causing errors...
Anybody knows why it is happening??
The Code is given below..

class A
{ public:
A()
{
cout<<"Its A"<<endl;
};

virtual show()
{
printf("Check");
printf("A");
}
};
class B : virtual public A
{ public:
B()
{
cout<<"Its B"<<endl;
}
//virtual
virtual show()
{
printf("Check");
printf("B");
}
};
class C:virtual public A
{ public:

C()
{
cout<<"Its C"<<endl;
}
virtual show(int x)
{
cout<<"x="<<endl;
printf("C Calling Show function of Class C\n");
printf("Check");
}
};
class D:virtual public B,virtual public C
{
public:
D()
{
cout<<"Its D"<<endl;
}
/*show()
{
printf("Check");
printf("D");
}*/
};

void main()
{
D obj;
obj.show(5);
getch();
}


And the error is..

warning C4250: 'D' : inherits 'B::show' via dominance : see declaration of 'show'
error C2385: 'D::show' is ambiguous
warning C4385: could be the 'show' in base 'B' of class 'D'
warning C4385: or the 'show' in base 'C' of class 'D'
error C2660: 'show' : function does not take 1 parameters

[weaknessforcats]

A coupole of things
1) your show() method has no return type. Assuming an int is C and this is deprecated in C++. You need to specify a return type.

2) you cannot overload functions between classes. That is, a show() in a base class cannot be overloaded by a show(int) in a derived class. Overloading means the method name is the same and the arguments are different.

This is OK:

class A
{
      void show();
      void show(int);
};
 

This is OK but the derived class cannot call show();

class A
{
    public:
      void show();
};
class B : public A
{
    public:
       void show(int);
};
int main()
{
    B obj;
    obj.show();   //Error: B::Show does not take 0 arguments
}
 

The show(int) dominates the show(). You would have to code:

main()
{
    B obj;
    obj.A::show();
}
 

Notice that public/private/protected are ignored in dominance. Dominance is based on the function name alone. The local name always dominates inherited names.

[sbvishal]

Thanks for your reply.
It made many things clear.

A coupole of things
1) your show() method has no return type. Assuming an int is C and this is deprecated in C++. You need to specify a return type.

2) you cannot overload functions between classes. That is, a show() in a base class cannot be overloaded by a show(int) in a derived class. Overloading means the method name is the same and the arguments are different.

This is OK:

class A
{
      void show();
      void show(int);
};
 

This is OK but the derived class cannot call show();

class A
{
    public:
      void show();
};
class B : public A
{
    public:
       void show(int);
};
int main()
{
    B obj;
    obj.show();   //Error: B::Show does not take 0 arguments
}
 

The show(int) dominates the show(). You would have to code:

main()
{
    B obj;
    obj.A::show();
}
 

Notice that public/private/protected are ignored in dominance. Dominance is based on the function name alone. The local name always dominates inherited names.