Abt.. Referring Subclass members thru base class object

[arul77]

class one {
public :
int a;
};

class two ublic one{
public:
int d;
}

class test {
union{
one a;
};
};

int main(){

test obj;
obj.a.d=10;
printf("%d",a.d);
return 0;
}

My problem is i need to have a class object in an union,[since there is a rule that union cannot contain members with constructors], so i created a dummy class one to overcome this,..

Error:
undefined variable d.
how to solve this...

 

[Nosferatu]

Well, either is a typO, either you were not paying attention, but inside the union, you have the class ONE which has NO MEMBER d...
It should work if you switch it to class two! [red]Nosferatu[/red]
We are what we eat...
There's no such thing as free meal...
once stated: methane@personal.ro

 

[mingis]

let use subclass with virtual data access methods instead of unions:

#include <stdio.h>

class one {
public :
int virtual GetData(void) = NULL;
void virtual PutData(int iData) = NULL;
};

class two ublic one {
public:
int d;

int virtual GetData(void);
void virtual PutData(int iData);
};

int two::GetData(void)
{
return(d);
}

void two:utData(int iData)
{
d=iData;
}

class test {
public:
one *one_ptr;
};

int main(){

test obj;
two act_data;

obj.one_ptr=(one *)&act_data;

obj.one_ptr->PutData(10);
printf(&quot;%d&quot;,act_data.d);

return 0;
}

 

[Zyrenthian]

mingis is correct. Take full advantage of the polymorphism with pointers. class two IS-A class one. By declaring the class as a specific type (no pointer) you can NOT assign any child class to it where as with a pointer, you get complete diversity.

Matt

 

[arul77]

All

Tx for your efforts..

I will use this solution