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Entry C# Interview Questions

Curated Entry-level C# interview questions for developers targeting entry positions. 13 questions available.

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C# Interview Questions & Answers

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Welcome to our comprehensive collection of C# interview questions and answers. This page contains expertly curated interview questions covering all aspects of C#, from fundamental concepts to advanced topics. Whether you're preparing for an entry-level position or a senior role, you'll find questions tailored to your experience level.

Our C# interview questions are designed to help you:

  • Understand core concepts and best practices in C#
  • Prepare for technical interviews at all experience levels
  • Master both theoretical knowledge and practical application
  • Build confidence for your next C# interview

Each question includes detailed answers and explanations to help you understand not just what the answer is, but why it's correct. We cover topics ranging from basic C# concepts to advanced scenarios that you might encounter in senior-level interviews.

Use the filters below to find questions by difficulty level (Entry, Junior, Mid, Senior, Expert) or focus specifically on code challenges. Each question is carefully crafted to reflect real-world interview scenarios you'll encounter at top tech companies, startups, and MNCs.

Questions

13 questions
Q1:

What are value types and reference types?

Entry

Answer

Value types: store data directly (int, bool, double, struct). Reference types: store a reference to memory (class, interface, array, string).
Quick Summary: Value types (int, bool, struct) store their actual data on the stack — copy one and you get two independent values. Reference types (class, string, array) store a pointer on the stack to heap data — copy a reference and both variables point to the same object. This distinction matters a lot when passing objects to methods.
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Q2:

What is boxing and unboxing?

Entry

Answer

Boxing: value type → converted to object (heap)Unboxing: object → converted back to value type


int x = 10;object obj = x;        // boxingint y = (int)obj;      // unboxing

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Q3:

What is garbage collection?

Entry

Answer

Automatic memory cleanup.

GC removes unused objects from the heap and prevents memory leaks.

Quick Summary: GC is .NET's automatic memory cleaner. Instead of freeing memory manually, the GC scans the heap, finds objects with no references, and reclaims that memory. It uses generations (Gen0, Gen1, Gen2) — young objects get collected more often since most objects are short-lived.
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Q4:

What is an interface?

Entry

Answer

A contract that defines method signatures without implementation.

A class must implement all the interface members.


interface IAnimal { void Speak(); }


Quick Summary: An interface is a contract — any class that implements it must have these methods and properties. No implementation, just signatures. This lets you write code against the interface rather than a specific class, making things easy to swap, test, and extend.
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Q5:

What is abstraction?

Entry

Answer

Hiding internal implementation and exposing only essential features.

Achieved using interfaces or abstract classes.

Quick Summary: Abstraction means hiding complex internals and exposing only what's needed. When you call List.Add(), you don't care how it resizes internally — you just use it. In C#, achieved through interfaces and abstract classes. Keeps code focused on what rather than how.
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Q6:

What is encapsulation?

Entry

Answer

Protecting data through access modifiers and properties.

private int age;

public int Age { get; set; }


Quick Summary: Encapsulation means bundling your data and the methods that work on it inside a class, and controlling who can access what. Fields stay private; you expose them through public properties. Prevents outside code from directly tampering with your object's internal state.
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Q7:

What are access modifiers in C#?

Entry

Answer

publicprivateprotectedinternalprotected internalprivate protected

Control visibility of classes and members.
Quick Summary: Access modifiers control visibility. public — anyone can access. private — only that class. protected — the class and its subclasses. internal — only within the same assembly. protected internal — subclasses or same assembly. Default for class members is private.
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Q8:

What is polymorphism?

Entry

Answer

Same method name behaves differently based on object type.
Two types:

  • Compile-time (method overloading)
  • Runtime (method overriding using override )

Quick Summary: Polymorphism means one interface, many behaviors. Call animal.Speak() on a Dog, Cat, or Bird — each responds differently through the same method signature. Achieved via method overriding (runtime) and method overloading (compile-time). One of OOP's most powerful features.
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Q9:

What is method overriding?

Entry

Answer

Child class provides new implementation for a parent class method.


public virtual void Speak() { }

public override void Speak() { }


Quick Summary: When a child class provides its own version of a parent class method, that's overriding. The parent marks it virtual, the child uses override. At runtime, even holding a base class reference, the child's version gets called — that's the whole point.
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Q10:

What is a constructor?

Entry

Answer

A special method executed when an object is created.

public Student() { }


Quick Summary: A constructor is a special method that runs automatically when you create an object with new. It sets up initial state. A class can have multiple constructors with different parameters. If you write none, C# provides a default parameterless one automatically.
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Q11:

What is a static constructor?

Entry

Answer

Runs only once per type — initializes static members.

static Student() { }


Quick Summary: A static constructor runs once — the very first time the class is used — and initializes static members. You cannot call it manually or pass parameters. Perfect for one-time setup like loading config or initializing shared resources.
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Q12:

What is an exception?

Entry

Answer

An error that occurs during runtime.

Handled using try…catch.

try { } 

catch(Exception ex) { }


Quick Summary: An exception is a runtime error — null reference, divide by zero, file not found, etc. Handle with try-catch-finally. Catch the specific exception type you expect, not the base Exception blindly. Always clean up resources in the finally block.
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Q13:

What is the difference between == and Equals()?

Entry

Answer

  • == → compares values for value types; references for reference types

    • Equals() → can be overridden for value comparison in reference types (e.g., string)

    • Quick Summary: For value types, both compare values. For reference types, == by default checks if they point to the same object in memory. Equals() can be overridden to compare content. Strings override both to compare content — that's why "hello" == "hello" is true even for different string objects.
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    People Also Ask - Related C# Questions

    What are value types and reference types?
    What is boxing and unboxing?
    What is garbage collection?
    What is an interface?
    What is abstraction?
    What is encapsulation?
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