say for an example
C extends B extends A
e.g. A is Grand, P is Parent, and C is Child
and A have a member variable called __data which is protected.
so would it be possible to initialize A's __data from C through C's Constructor
like C::C():__data(0)
My Compiler (g++) fires error saying Class C doesnt have a field named __data
__data should be initialized by A's constructor. B should call A's constructor appropriately to make sure that it is initialized correctly. C should call B's constructor correctly to make sure that it is initialized correctly.
But as its a protected data member shouldn't it be able to access it though ??
Yes, but not in the initializer list... a member can only be in the initializer list once because that is where it's constructor is called. It will automatically be constructed by its class (A in this case) whether you type it in the list or not, so adding it to C's list would double-construct, which is not allowed.
You can access it inside C's constructor, but that is usually not as good of an idea as accessing it through A's interface.
Ok Thanks
And avoid names starting with "__" like the plague, because they are reserved for compiler implementation.