Learning C# 3.0

Summary

• An interface is a contract through which a class guarantees that it will implement certain methods, provide certain properties and indexers, and support certain events, all of which are specified in the interface definition.

• You cannot create an instance of an interface. To access the interface methods, you need to create an instance of a class that implements that interface.

• You declare an interface much like you would a class, but using the keyword interface. You can apply access modifiers to the interface, as you would with a class.

• In the interface definition, the method declarations cannot have access modifiers.

• To implement an interface on a class, you use the colon operator, followed by the name of the interface, similar to the syntax for inheritance.

• Classes can derive from no more than one class, but can implement any number of interfaces. If a class has a base class and one or more interfaces, the base class must be listed first (after the colon). Separate the base class and interface names by commas.

• When you define a class that implements an interface, you must then implement all the required members of that interface.

• In situations where you don’t know what type of object you have, and you know only that the object implements a specific interface, you can create a reference to the interface and assign the object to that reference, providing you with access to the implemented interface methods.

• You can use the is operator to determine whether an object derives from a ...