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There is a concept of Object and Class in C++, because it is an Object Oriented Programming Language. Each object can be related to a type, which is its class. An important consideration of a class is that it specifies the message interface that is the messages that can be sent to that type/class of the objects. All object of a particular can receive the same messages, but may behave differently. This leads to an important conclusion.

Where as structures can not be used for message interface. It is only used for same memory allocation for different types of data.

The class acts as a guard and thus provides information hiding and an encapsulations.