Multiple interface implementation in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does multiple interface implementation mean in C#?

It means a class can use more than one interface at the same time, allowing it to promise to do multiple sets of actions.

beginner

How do you declare a class that implements two interfaces named <code>IWalk</code> and <code>IRun</code>?

Use a comma to separate interfaces like this:<br><pre>class Animal : IWalk, IRun { }</pre>

intermediate

Can a class implement two interfaces that have methods with the same name?

Yes, but you may need to use explicit interface implementation to avoid confusion and specify which method belongs to which interface.

intermediate

What is explicit interface implementation in multiple interface implementation?

It is a way to write methods so they only work when accessed through the interface, helping to handle method name conflicts.

beginner

Why is multiple interface implementation useful?

It helps a class to follow many different contracts or roles, making code flexible and easier to organize.

How do you declare a class that implements two interfaces IRead and IWrite?

A class File implements IRead, IWrite { }

B class File : IRead & IWrite { }

C class File : IRead, IWrite { }

D class File : IRead.IWrite { }

In C#, use a colon and separate interfaces with commas: class File : IRead, IWrite { }.

If two interfaces have a method with the same name, how can a class implement both?

A Use explicit interface implementation

B Rename one method in the class

C You cannot implement both

D Use inheritance instead

Explicit interface implementation lets you specify which method belongs to which interface.

Which keyword is used to implement interfaces in a class?

A :

B implements

C extends

D inherits

C# uses a colon (:) to implement interfaces in a class.

Can a class implement zero or more interfaces?

A No, at least one

B Yes, zero or more

C No, only one

D Only zero

A class can implement no interfaces or many interfaces.

What happens if a class implements an interface but does not provide all methods?

A Interface methods are ignored

B It works fine

C Runtime error

D Compilation error

C# requires all interface methods to be implemented, or the code will not compile.

Explain how multiple interface implementation works in C# and why it is useful.

Think about how a class can promise to do many things by following many contracts.

Describe explicit interface implementation and when you would use it.

Consider when two interfaces have the same method name.