Essential C# Interview Questions and Answers for Beginners

This summary provides an overview of key concepts and common questions encountered in C# interviews, particularly sourced from Tutorialspoint. Aimed at beginners, this guide is designed to help you grasp fundamental concepts and effectively prepare for interviews.

Key Concepts in C#

What is C#?

• C# (pronounced "C sharp") is a modern, object-oriented programming language developed by Microsoft.
• It is primarily used for developing applications on the .NET framework.

Features of C#

• Object-Oriented: Supports concepts like inheritance, encapsulation, and polymorphism.
• Type Safety: Provides strong type checking at compile-time.
• Automatic Garbage Collection: Manages memory automatically to avoid memory leaks.
• Cross-Platform: Can be used to create applications that run on various platforms.

Common Interview Questions

1. What is the difference between `==` and `Equals()`?

• == compares object references (identity) for reference types and values for value types.
• Equals() checks for value equality and can be overridden in custom classes.

Example:

string str1 = new string("hello");
string str2 = new string("hello");
Console.WriteLine(str1 == str2); // True (compares values)
Console.WriteLine(str1.Equals(str2)); // True (compares values)

2. Explain the concept of inheritance.

• Inheritance allows a class (derived class) to inherit properties and methods from another class (base class).
• Promotes code reusability.

Example:

class Animal {
    public void Eat() {
        Console.WriteLine("Eating...");
    }
}

class Dog : Animal {
    public void Bark() {
        Console.WriteLine("Barking...");
    }
}

3. What are interfaces?

• An interface is a contract that defines a set of methods and properties that implementing classes must fulfill.
• Interfaces support multiple inheritance.

Example:

interface IDog {
    void Bark();
}

class Labrador : IDog {
    public void Bark() {
        Console.WriteLine("Woof!");
    }
}

4. What is a delegate?

• A delegate is a type that represents references to methods with a specific parameter list and return type.
• Delegates are used for implementing event handling.

Example:

public delegate void Notify();  // delegate declaration

public class Process {
    public event Notify ProcessCompleted; // event declaration

    public void StartProcess() {
        // Process logic...
        OnProcessCompleted();
    }

    protected virtual void OnProcessCompleted() {
        ProcessCompleted?.Invoke(); // invoke the event
    }
}

Conclusion

Understanding these key concepts and common questions can greatly assist beginners in learning C# and preparing for interviews. Familiarity with the syntax and features of C# will enhance your programming skills and boost your confidence in discussions related to the language.