How do you declare an interface in C++?

Question

How do I setup a class that represents an interface? Is this just an abstract base class?

Answer 1

Need to clarify here what you mean by "interface."

Every class in C++ has interface, being everything that is declared as public. This is the only way to access what is within a class, everything else is encapsulated by private. The public section is what you can publish for the World to use, and once done they need to be maintained. In some instances, the public interface is a contract between you and the users of your class; changing an interface can cause some severe issues.

An abstract class in C++ is a class that will never be instantiated; no objects of this type of class can ever be declared, no new used to create such an object. Abstract classes are only ever used as a base of other classes. Abstract classes are used to set "expectations" for a class; your derived classes are expected to fill them in.

Now, given this information, what do you mean when you ask, "How do I setup a class that represents an interface?"