15 Technical Interview Questions for Freshers Applying for Software Developer Engineer Positions in MNCs like TCS, Wipro, Infosys, and Siemens

OOP Principles:

Polymorphism: The ability to present the same interface for different underlying forms (data types). Example: A method Draw(Shape s) can take any shape (Circle, Rectangle).

Encapsulation: Bundling data and methods that operate on that data within a single unit (class). Example: A Car class that has properties like Color and methods like Drive().

Abstraction: Hiding complex implementation details and showing only the essential features. Example: An abstract class Shape with a method Draw() that derived classes implement.

Inheritance: A mechanism to create a new class using properties and methods of an existing class. Example: A SportsCar class inheriting from Car.

Design Patterns:

Observer: A way to notify multiple objects about state changes. Example: A NewsPublisher that notifies all subscribed Subscribers when news is published.

Singleton: Ensures a class has only one instance and provides a global access point. Example: A logging class that manages logs in a single instance.

Interface vs. Abstract Class:

Abstract Class: Can contain both abstract methods and implemented methods. Use when classes share common behavior but may also have unique methods.

Interface: Can only contain method signatures (no implementation). Use when multiple classes might implement the same methods differently.

Exception Handling in C#:

try
{
// Code that may throw an exception
int result = 10 / 0;
}
catch (DivideByZeroException ex)
{
Console.WriteLine("Cannot divide by zero: " + ex.Message);
}
finally
{
// Code that runs regardless of exception
Console.WriteLine("Execution completed.");
}

.NET Framework:

.NET 5/6: Unifies .NET Core and .NET Framework into a single platform for all types of applications.

.NET Framework: A platform for building Windows applications.

.NET Core: A cross-platform version of .NET for building cloud-based applications.

RESTful API:

REST stands for Representational State Transfer. It uses standard HTTP methods (GET, POST, PUT, DELETE) for CRUD operations and is stateless. Example: Designing a GET /users endpoint to retrieve users.

Connecting C# to SQL:

• Use ADO.NET or Entity Framework. Example:

using (SqlConnection conn = new SqlConnection(connectionString))
{
 conn.Open();
SqlCommand cmd = new SqlCommand("SELECT * FROM Users", conn);
SqlDataReader reader = cmd.ExecuteReader();
}

Entity Framework:

It is an ORM (Object-Relational Mapper) that simplifies data access by allowing developers to work with databases using C# objects rather than SQL queries.

Web Application Security:

Implement HTTPS, input validation, output encoding, and security headers. Use authentication and authorization mechanisms to protect sensitive data.

Role of Angular:

Angular is a platform for building web applications using TypeScript. Key features include two-way data binding, dependency injection, and a modular architecture.

Components vs. Services:

Services: Share data and logic across components. They are used for operations like fetching data from APIs.

Components: Control views and UI. They manage data binding and user interactions.

State Management in Angular:

Strategies include using services for shared state, the Redux pattern, or libraries like NgRx for complex state management.

Unit Testing:

• Unit testing verifies that individual components work as expected. Example using NUnit:

[Test]
public void TestAdd()
{
    Assert.AreEqual(4, Add(2, 2));
}

Testing Tools:

Common tools include NUnit, xUnit, and Moq for mocking. Experience can include writing test cases to ensure code quality.

DevOps:

DevOps is a culture that integrates development and operations to shorten the development lifecycle. Tools include Jenkins for CI/CD, Docker for containerization, and Kubernetes for orchestration.

Memory Management Differences:

C++: Developers manually manage memory using new and delete. This allows for fine control but requires careful management to avoid leaks.

C#: Automatic garbage collection manages memory.