How data hiding is possible within a class in c plus plus?

A class is a description of an object, its attributes, and its methods. Its not a lot different than primitive types, such as int. int a; /* instantiate object of type int and call it a */ person b; /* instantiate object of type personand call it b */ The difference is that person is declared in a class specification, and is potentially much more complex than int. Still, you can think of both in the same context. The attributes (member variables) of a class contain the state of each instance of that class. You can (and usually do) declare those attributes as private, which means that only methods of the class can access them. This is data hiding. With data hiding, you can encapsulate the functionality of a class, exposing only the needed public interface. This way, if you need to change the way a class works internally, such as storing the person's name in unicode string instead of char string, that change can, if the interface is correct, be totally transparent to the user of the class.