Mastering C#: Essential Interview Questions & Answers for Developers

This comprehensive guide prepares you for C# interviews by covering a wide range of fundamental and intermediate concepts. We explore core C# features, including object-oriented programming principles (classes, constructors, inheritance, polymorphism), access modifiers, and exception handling. This resource provides detailed answers to frequently asked C# interview questions, covering data structures (arrays, ArrayLists), collections, interfaces, and delegates. Learn about crucial concepts like serialization, garbage collection, and the `lock` statement for thread synchronization. This guide will equip you with the knowledge to confidently address a broad spectrum of C# interview questions.

Top C# Interview Questions and Answers

What is C#?

C# is a versatile, modern programming language developed by Microsoft. It's object-oriented, making it suitable for building a wide variety of applications. C# code is compiled into an intermediate language (MSIL) that runs on the .NET framework, providing platform independence.

Reasons for C#'s Creation

C# was designed to work with the Common Language Infrastructure (CLI), a set of standards that enable different programming languages to run on various platforms. This interoperability is a key advantage.

Reasons to Use C#

• Easy to Learn: Relatively straightforward syntax for beginners.
• Object-Oriented: Supports encapsulation, inheritance, and polymorphism.
• Component-Oriented: Facilitates building reusable components.
• Structured: Promotes well-organized and maintainable code.
• Cross-Platform Compatibility (via .NET): Runs on Windows and other platforms.
• High Performance: Compiled to efficient intermediate language.
• Part of the .NET Framework: Accesses a rich set of libraries and tools.

C# Access Modifiers: `public`, `static`, `void`

• public: Accessible from anywhere.
• static: Belongs to the class itself, not a specific instance.
• void: Indicates a method doesn't return a value.

Constructors in C#

Constructors are special methods within a class that have the same name as the class. They are automatically called when an object of the class is created to initialize the object's member variables.

Types of Constructors in C#

• Default Constructor
• Parameterized Constructor
• Copy Constructor
• Static Constructor
• Private Constructor

Static Constructor in C#

A static constructor is used to initialize static members of a class. It's called only once, the first time the class is accessed.

Method Overloading in C#

Method overloading allows you to have multiple methods with the same name but different parameters (different number or types of parameters) within the same class. The compiler determines which method to call based on the arguments provided.

Method Overriding in the Same Class

Method overriding (as opposed to overloading) is not possible within the same class. Overriding occurs when a derived class provides a new implementation for a method inherited from a base class.

Arrays in C#

Arrays are used to store a fixed-size sequence of elements of the same type. C# supports:

• Single-dimensional arrays.
• Multi-dimensional arrays.
• Jagged arrays (arrays of arrays, where each inner array can have a different size).

ArrayList in C#

An ArrayList is a dynamic array that can grow or shrink as needed. It's flexible but generally less efficient than a regular array for accessing elements.

Collections in C#

Collections are classes providing ways to store and manage groups of objects. They implement the ICollection interface.

Interfaces in C#

An interface defines a contract that classes can implement. It specifies methods, properties, and events without providing their implementation.

lock Statement in C#

The lock statement is used for thread synchronization. It ensures that only one thread can access a critical section of code at a time, preventing race conditions.

Serialization in C#

Serialization converts an object's state into a stream of bytes, allowing you to store the object or transmit it over a network. Deserialization is the reverse process.

Declaring a Property in C#

private int _personID = 0; // Backing field

public int PersonID {
    get { return _personID; }
    set { _personID = value; }
}
        

Early Binding vs. Late Binding in C#

Access Modifiers in C#

Access modifiers control the visibility and accessibility of class members:

• public: Accessible from anywhere.
• private: Accessible only within the class.
• protected: Accessible within the class and its derived classes.
• internal: Accessible only within the same assembly.
• protected internal: Accessible within the same assembly or derived classes.

Abstract Class vs. Interface in C#

Dispose() vs. Finalize()

Method Overloading vs. Method Overriding

Object Pool in .NET

An object pool is a technique for reusing objects to reduce the overhead of object creation and improve performance.

Delegates in C#

A delegate is an object that holds a reference to a method. It's essentially a type-safe function pointer.

Hashtable in C#

A Hashtable stores key-value pairs, allowing you to access values using their associated keys.

Reflection in C#

Reflection allows you to inspect and manipulate types and their members at runtime.

Garbage Collection in C#

Garbage collection is the automatic process of reclaiming memory occupied by objects that are no longer being used.

Additional Interview Resources

Here are some additional interview resources covering related technologies:

• Java Basics Interview Questions
• Java OOPs Interview Questions
• Java Multithreading Questions
• Java String & Exception Questions
• Java Collection Interview Questions
• JDBC Interview Questions
• Servlet Interview Questions
• JSP Interview Questions
• Spring Interview Questions
• Hibernate Interview Questions
• PL/SQL Interview Questions
• SQL Interview Questions
• Oracle Interview Questions
• Android Interview Questions
• SQL Server Interview Questions
• MySQL Interview Questions