Practice c-sharp Quizzes

Boost your knowledge of c-sharp with DevBrainiac's interactive quizzes that make learning faster and more effective. Each quiz focuses on real-world concepts, helping you improve accuracy, understand fundamentals and prepare better for technical interviews. Suitable for beginners and professionals alike, our c-sharp quizzes offer a focused, practical approach to mastering the topic.

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Learn c-sharp step by step with interactive quizzes designed for beginners and learners revising key concepts. Build a strong foundation with clear, structured practice in c-sharp.

Question 1

Which of the following is true about C#?

C# is a statically-typed language

C# supports multiple inheritance directly

C# does not support garbage collection

C# does not support object-oriented programming

None of the above

Question 2

What is the default access modifier for a class in C#?

Private

Internal

Protected

public

Question 3

Which of the following is NOT a valid C# data type?

double

real

float

int

Question 4

What is the output of the following C# code?

int a = 5, b = 2;
double result = a / b;
Console.WriteLine(result);

2.0

Compilation error

2.5

Question 5

Which of the following statements about C# constructors is true?

A constructor must always have a return type

A class can have only one constructor

A constructor can be called explicitly like a normal method

A constructor is automatically called when an object is created

Question 6

What is the keyword used to inherit a class in C#?

implements

extends

inherits

: (colon)

Question 7

What is the difference between == and .Equals() in C#?

Both are the same and compare object references

== compares values, whereas .Equals() compares references

== compares references, whereas .Equals() compares values

None of the above

Question 8

What will be the output of the following code?

string s1 = "Hello";
string s2 = "Hello";
Console.WriteLine(s1 == s2);
Console.WriteLine(s1.Equals(s2));

True True

True False

False False

False True

Question 9

Which of the following statements about C# interfaces is true?

An interface can contain constructors

An interface can have fields

An interface cannot be inherited by another interface

An interface can provide default method implementation

Question 10

What is the purpose of the using statement in C#?

It imports namespaces

It defines scope for disposing objects

It handles exceptions

Both 1 and 2

Question 11

What is the output of the following C# code?

using System;

class Program
{
    static void Main()
    {
        int x = 10;
        object obj = x;
        int y = (int)obj;
        Console.Write(y);
    }
}

NullReferenceException

Compilation error

Runtime error

Question 12

What is the correct way to define a nullable integer in C#?

int num = nullable;

null int num;

nullable<int> num = null;

int? num = null;

Question 13

Which of the following is true about C# properties?

Properties must always have both get and set

Properties cannot be read-only

Properties are just variables with additional syntax

Properties can have different access modifiers for get and set

Question 14

Which keyword is used to prevent a class from being inherited?

private

abstract

static

sealed

Question 15

Which of the following correctly implements an interface in C#?

interface ITest { void Show(); }
class MyClass { public void Show() { Console.WriteLine("Hello"); } }

interface ITest { void Show(); }
class MyClass : ITest { void Show() { Console.WriteLine("Hello"); } }

interface ITest { void Show(); }
class MyClass : ITest { public void Show() { Console.WriteLine("Hello"); } }

interface ITest { void Show(); }
class MyClass : ITest { protected void Show() { Console.WriteLine("Hello"); } }

Question 16

What will be the output of the following LINQ query?

var numbers = new List<int> { 2, 3, 4, 5 };
var result = numbers.Where(n => n % 2 == 0);
Console.WriteLine(result.Count());

Question 17

What will happen if you call ToString() on a null object in C#?

It throws a NullReferenceException

It returns an empty string

It returns "null"

It depends on the object's type

Question 18

What is the output of the following C# code?

async Task<int> GetNumberAsync() { return 5; }
async Task Main()
{
    Task<int> task = GetNumberAsync();
    Console.WriteLine("Before await");
    int result = await task;
    Console.WriteLine($"Result: {result}");
}

Before await
Result: 5

Result: 5
Before await

Random execution order

Compilation error

Question 19

Which of the following statements about Dictionary in C# is true?

Keys in a dictionary must be unique

A dictionary allows only string keys

A dictionary stores elements in a sorted order

All of the above

Question 20

What type of inheritance is not supported in C#?

Hierarchical Inheritance

Multiple Inheritance

Multilevel Inheritance

Single Inheritance

Question 21

Which of the following is true about abstract classes in C#?

Abstract classes can be instantiated.

Abstract classes must have at least one abstract method.

An abstract class can have concrete methods.

Interfaces and abstract classes are the same.

Question 22

Which keyword prevents method overriding in C#?

private

abstract

final

sealed

Question 23

Which of the following best describes the .NET framework?

A hardware component

An operating system

A development platform

A database management system

Question 24

Which language influenced the development of C# the most?

PHP

Python

C++

Java

Question 25

What is the primary runtime used to execute C# programs?

Dynamic Link Library (DLL)

Java Virtual Machine (JVM)

Common Runtime Interface (CRI)

Common Language Runtime (CLR)

Question 26

If you receive a 'namespace not found' error, what is the likely cause?

Typo in the class name

Incorrect file extension

Missing 'using' directive

Missing semicolon

Question 27

What will be the output of the following code?

int a = 5, b = 2;
Console.WriteLine(a / b);

2.5

Error

Question 28

Which operator has the highest precedence in C#?

()

Question 29

What does the ?? operator do in C#?

Checks type

Performs bitwise OR

Performs null-coalescing

Checks equality

Question 30

What is the result of this expression: true || false && false?

false

Error

Cannot determine

true