Why use interfaces in PHP (OOP)

Posted on 16th Feb 2014 by admin

I am learning OOP in PHP and its been a pretty good learning experience so far. What I didn't understand at all is interfaces. I understand the implications of multiple inheritance, and interface is used just to solve that. But what's the use?
If we have to define the function in derived class why use interface, why not directly declare and define it inside the derived class?
Am I missing something or is it really useless?

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