Why do we need observer?

In control theory, a state observer or state estimator is a system that provides an estimate of the internal state of a given real system , from measurements of the input and output of the real system. It is typically computer-implemented, and provides the basis of many practical applications.

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What is Observer pattern in C++?

Observer in C++ Observer is a behavioral design pattern that allows some objects to notify other objects about changes in their state . The Observer pattern provides a way to subscribe and unsubscribe to and from these events for any object that implements a subscriber interface.

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