In C#, what is the correct way to implement explicit interface implementation?

The correct answer is B: private void InterfaceName.MethodName() { }. Explicit interface implementation is always private by convention and accessed through interface reference only, not through class instance directly.

What is the output of the following code? class Animal { public virtual void Sound() { Console.WriteLine("Generic Sound"); } } class Dog : Animal { public override void Sound() { Console.WriteLine("Bark"); } } Dog dog = new Dog(); dog.Sound();

The correct answer is B: Bark. Polymorphism ensures that the overridden method in Dog class executes. The override keyword allows the derived class to provide its specific implementation.

Which of the following is the latest version of ASP.NET as per 2024-2025?

The correct answer is B: ASP.NET Core 8.0. ASP.NET Core 8.0 is the latest unified platform as of 2024-2025, replacing the older ASP.NET Framework.

In a real-time cache system with limited memory, which collection supports automatic eviction of least recently used items?

The correct answer is B: MemoryCache from System.Runtime.Caching. MemoryCache provides LRU-style eviction and memory management policies. Basic collections don't have built-in LRU functionality.

What is the difference between 'var' and explicit type declaration in C#?

The correct answer is B: var is implicitly typed but strongly typed at compile time. var is implicitly typed, meaning the compiler infers the type at compile time, but it's still strongly typed. It's not dynamic.

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OOP in C#

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Difficulty: All Easy Medium Hard 21–24 of 24

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All Basics & Syntax 100 OOP in C# 100 Collections 71 ASP.NET Basics 19

Q.21 Easy OOP in C#

Which of the following correctly demonstrates an abstract class with an abstract method in C#?

A public abstract class Base { public abstract void Method(); }

B public class Base { public abstract void Method(); }

C public abstract class Base { public void Method(); }

D public sealed abstract class Base { public abstract void Method(); }

Correct Answer: A. public abstract class Base { public abstract void Method(); }

EXPLANATION

An abstract class uses the 'abstract' keyword, and abstract methods must be declared without implementation inside abstract classes.

Test

Q.22 Easy OOP in C#

In C#, can a class inherit from multiple classes?

A Yes, always

B No, C# does not support multiple inheritance

C Yes, but only if they are abstract

D Yes, using the 'multiple' keyword

Correct Answer: B. No, C# does not support multiple inheritance

EXPLANATION

C# does not support multiple class inheritance to avoid the diamond problem. However, a class can implement multiple interfaces.

Test

Q.23 Easy OOP in C#

Which keyword is used to create a derived class in C#?

A extends

B inherits

C :

D ->

Correct Answer: C. :

EXPLANATION

In C#, the colon (:) is used to indicate inheritance. For example, 'class Child : Parent' creates a derived class.

Test

Q.24 Easy OOP in C#

In C#, what is the default access modifier for class members?

A public

B private

C protected

D internal

Correct Answer: B. private

EXPLANATION

The default access modifier for class members in C# is 'private', which restricts access to within the class only.

Test

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