Where did the concept of Interfaces come from?

Question

In c#, we have interfaces. Where did these come from? They didn\'t exist in c++.

Answer 1

i've seen the keyword interface first in java, but they are much older than that.

the same concept exists in c++ but it is not exactly the same. They are called "pure virtual classes"

http://en.wikipedia.org/wiki/Virtual_function

They exists with different syntax but are there to allow polymorphism in OOP.