Multiple interface implementation in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a class that implements two interfaces.

C Sharp (C#)

interface IFirst { void MethodA(); }
interface ISecond { void MethodB(); }

class MyClass : [1] {
    public void MethodA() { }
    public void MethodB() { }
}

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

AIFirst, ISecond

BIFirst ISecond

CIFirst & ISecond

DIFirst | ISecond

Attempts:

3 left

💡 Hint

Common Mistakes

Using spaces or symbols instead of commas between interface names.

Trying to use '&' or '|' which are not valid here.

In C#, multiple interfaces are implemented by listing them separated by commas.

2fill in blank

medium

Complete the code to explicitly implement the MethodA from IFirst interface.

C Sharp (C#)

interface IFirst { void MethodA(); }
class MyClass : IFirst {
    void [1].MethodA() {
        Console.WriteLine("First");
    }
}

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AMethodA

BMyClass

CISecond

DIFirst

Attempts:

3 left

💡 Hint

Common Mistakes

Using the class name instead of the interface name.

Omitting the interface name prefix.

Explicit interface implementation requires prefixing the method with the interface name.

3fill in blank

hard

Fix the error in the code by completing the interface implementation syntax.

C Sharp (C#)

interface IFirst { void MethodA(); }
interface ISecond { void MethodB(); }

class MyClass : IFirst [1] ISecond {
    public void MethodA() { }
    public void MethodB() { }
}

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A,

B;

C&

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using semicolon or other symbols instead of comma.

Leaving out the separator entirely.

Interfaces must be separated by commas in the class declaration.

4fill in blank

hard

Fill both blanks to complete the explicit implementation of two interfaces in the class.

C Sharp (C#)

interface IFirst { void MethodA(); }
interface ISecond { void MethodB(); }

class MyClass : IFirst, ISecond {
    void [1].MethodA() {
        Console.WriteLine("First");
    }
    void [2].MethodB() {
        Console.WriteLine("Second");
    }
}

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AIFirst

BMyClass

CISecond

DMethodA

Attempts:

3 left

💡 Hint

Common Mistakes

Using the class name instead of interface names.

Mixing up interface names between methods.

Explicit implementation requires prefixing each method with its interface name.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps interface names to method names if method name length is greater than 5.

C Sharp (C#)

var methods = new Dictionary<string, string[]> {
    { "IFirst", new string[] { "MethodA", "Init" } },
    { "ISecond", new string[] { "MethodB", "Start" } }
};

var filtered = methods.ToDictionary(
    [1] => [2],
    [3] => [3].Value.Where(m => m.Length > 5).ToArray()
);

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Akvp

Bkvp.Key

Ckvp.Value

Dm

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong variable names in lambdas.

Mixing keys and values in the wrong places.

In ToDictionary, the first lambda gets the key (kvp.Key), the second gets the value (kvp.Value).