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

Well there wasn't any language integrated mechanism syntax for it, but you can achieve interfaces in C++ with pure virtual classes.

class IFoo
{
public:
  void Bar() =0;
  void Bar2() =0;
};

class Concrete : public IFoo
{
public:
  void Bar() { ... }
  void Bar2() { ... }
}