Why interfaces are needed in C Sharp (C#) - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an interface named IAnimal.

C Sharp (C#)

public interface [1] { string Speak(); }

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AAnimalInterface

BAnimal

CIAnimal

DInterfaceAnimal

Attempts:

3 left

💡 Hint

Common Mistakes

Using class names instead of interface names

Not starting interface name with 'I'

The interface name should start with 'I' by convention, so IAnimal is correct.

2fill in blank

medium

Complete the code to make the Dog class implement the IAnimal interface.

C Sharp (C#)

public class Dog : [1] { public string Speak() { return "Woof!"; } }

Drag options to blanks, or click blank then click option'

ASpeakable

BDogInterface

CAnimal

DIAnimal

Attempts:

3 left

💡 Hint

Common Mistakes

Using a class name instead of interface

Forgetting to implement the interface

The class Dog implements the interface IAnimal using a colon.

3fill in blank

hard

Fix the error in the code by completing the interface method declaration.

C Sharp (C#)

public interface IAnimal { string [1](); }

Drag options to blanks, or click blank then click option'

ASpeak

BRun

CSleep

DEat

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different method name than in the class

Omitting the method name

The interface requires a method named Speak to be implemented by classes.

4fill in blank

hard

Fill both blanks to create a dictionary that maps animal names to their sounds using interface methods.

C Sharp (C#)

var sounds = new Dictionary<string, string> { {"Dog", dog.[1]()}, {"Cat", cat.[2]()} };

Drag options to blanks, or click blank then click option'

ASpeak

BMeow

DBark

Attempts:

3 left

💡 Hint

Common Mistakes

Using different method names for dog and cat

Using animal sounds as method names

Both dog and cat objects implement the Speak method from the interface.

5fill in blank

hard

Fill all three blanks to define an interface, implement it in a class, and call its method.

C Sharp (C#)

public interface [1] { string [2](); } public class Bird : [3] { public string Speak() { return "Chirp!"; } }

Drag options to blanks, or click blank then click option'

AIAnimal

BSpeak

DIBird

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatching interface and class names

Using method names not declared in the interface

The interface is named IAnimal, the method is Speak, and the class Bird implements IAnimal.