Accessing derived class data members

[Prashanth Kumar B R]

How can i access a public data member of a derived class with a pointer to the base class.

class Base
{
public:
Base(){};
virtual ~Base(){};
virtual bool decode(AOC_Stri ng element_text) ;
}
class Derived: pubilc Base
{
pubilc:
int ele;
bool decode(AOC_Stri ng element_text)
{
}
}

Base *Ptr = (Base *)new(Derived);

Ptr->decode("123" ); //works fine
Ptr->ele; //this throws an error... why is this wrong, what's the right way

Many Thanks

[Meetee]

How can i access a public data member of a derived class with a pointer to the base class.

class Base
{
public:
Base(){};
virtual ~Base(){};
virtual bool decode(AOC_Stri ng element_text) ;
}
class Derived: pubilc Base
{
pubilc:
int ele;
bool decode(AOC_Stri ng element_text)
{
}
}

Base *Ptr = (Base *)new(Derived);

Ptr->decode("123" ); //works fine
Ptr->ele; //this throws an error... why is this wrong, what's the right way

Many Thanks

Pointer *Ptr is a base pointer, and decode is a virtual method. So base pointer can access this method and not ele.

[Prashanth Kumar B R]

Pointer *Ptr is a base pointer, and decode is a virtual method. So base pointer can access this method and not ele.

Is there any way by which i can access the Element of the derived class from *Ptr?

[weaknessforcats]

Base *Ptr = (Base *)new(Derived);

Ptr->decode("123" ); //works fine
Ptr->ele; //this throws an error... why is this wrong, what's the right way

Stop casting. The code should be:

[code=cpp]
Base *Ptr = new Derived;

Ptr->decode("123" ); //works fine
Ptr->ele; //this throws an error... why is this wrong, what's the right way
[/code]

Ptr is a Base* so it can access only Base members.

If you need to use Ptr to access ele, then you need to design your classes to support the Visitor design pattern.