How to avoid the situation

[vivekgalatage]

#include
#include
class A
{
int a;
public:
A()
{
a=100;
}

int get()
{
return a;
}
};

int main()
{
A *a=new A();
int *p=(int *)a;

printf("%d\n",a->get());

*p=200;

printf("%d\n",a->get());

system("pause");
}

its out put is -
100
200

so can any body help me to avoid this situation bcoz as we can observ the class definition we can access the private members.

[Chainsaw]

What are you trying to avoid? Hacking? You hacked this and claim that you can access the private member a->a; All the 'private' designation means is that you can't access it via referencing it normally in the compiler; there's no implied protection of the memory area.

Try "a->a = 200;" and the compiler will tell you that you can't access a private member. That is a COMPILE time protection; what you demonstrated is a RUNTIME access.

Incidentally, add this to your definition of the class A:

virtual ~A() { a = 0; }

and try your hack. The output will read 100 and 100 and then your program will crash, because the vtable pointer for the destructor was set to 200.