All remaining Dotnet Developer Interview questions and answers which I was facing

Here are the answers for the remaining questions:

14. Multiple Return Types from a Method

Answer: You can return multiple values from a method using Tuple, out parameters, or a custom object.

Example using Tuple:

public (int, string) GetMultipleValues()
{
    return (1, "Result");
}
var result = GetMultipleValues();
Console.WriteLine($"ID: {result.Item1}, Value: {result.Item2}");



---

15. Private Constructor

Answer: A private constructor is used to prevent the instantiation of a class from outside the class. It’s typically used in singleton patterns.

Example:

public class MyClass
{
    private MyClass() { }  // Private constructor
}



---

16. Method Hiding

Answer: Method hiding occurs when a method in a derived class has the same name and signature as one in its base class but is marked with the new keyword. This hides the base class implementation.

Example:

public class BaseClass
{
    public void Display() { Console.WriteLine("Base Display"); }
}
public class DerivedClass : BaseClass
{
    public new void Display() { Console.WriteLine("Derived Display"); }
}



---

17. Difference Between Interface and Abstraction

Answer:

Interface: Defines a contract that classes must follow, but does not provide any implementation. All methods are abstract.

Abstract Class: Can have both abstract methods (without implementation) and concrete methods (with implementation).


Example:

public interface IShape { void Draw(); }
public abstract class Shape { public abstract void Draw(); public void Fill() { } }



---

18. Difference Between HTTP GET and HTTP POST

Answer:

GET: Used to retrieve data from the server. Data is sent in the URL.

POST: Used to submit data to the server. Data is sent in the body of the request.




---

19. Web API Security

Answer: Security can be achieved using authentication mechanisms such as JWT tokens, OAuth, or API keys. HTTPS should be enforced, and sensitive data should be encrypted.

Example using JWT:

services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
        .AddJwtBearer(options => {
            options.TokenValidationParameters = new TokenValidationParameters
            {
                ValidateIssuer = true,
                ValidateAudience = true,
                ValidateLifetime = true,
                ValidateIssuerSigningKey = true,
                IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes("secret_key"))
            };
        });



---

20. Difference Between IEnumerable and IQueryable

Answer:

IEnumerable: Executes on the client side and iterates over collections in memory.

IQueryable: Executes on the server side and translates LINQ queries into SQL queries.


Example:

IEnumerable<Employee> employees = context.Employees.ToList();
IQueryable<Employee> queryableEmployees = context.Employees.Where(e => e.Salary > 50000);



---

21. SOLID Principles

Answer: SOLID stands for:

S: Single Responsibility Principle

O: Open/Closed Principle

L: Liskov Substitution Principle

I: Interface Segregation Principle

D: Dependency Inversion Principle


These principles help in writing clean, maintainable, and scalable code.



---

22. Method Access Restriction in Child Class

Answer: You can restrict method access by using the sealed or private keywords.

Example:

public class BaseClass
{
    public void MethodA() { }
    private void MethodB() { } // Private to restrict access
}



---

23. Method Overloading vs Method Overriding

Answer:

Method Overloading: Same method name, but different signatures (parameters or return types).

Method Overriding: Replaces a base class method in a derived class. Must have the same signature.




---

24. String Reverse Program Without Predefined Functions

string ReverseString(string input)
{
    char[] charArray = new char[input.Length];
    for (int i = 0, j = input.Length - 1; i <= j; i++, j--)
    {
        charArray[i] = input[j];
        charArray[j] = input[i];
    }
    return new string(charArray);
}


---

25. LINQ Query for Joins

var result = from e in context.Employees
             join d in context.Departments on e.DepartmentId equals d.Id
             select new { e.Name, DepartmentName = d.Name };


---

26. Async Programming and Task Parallel Library (TPL)

Async Programming: Allows for non-blocking operations using async and await keywords.

TPL: Task Parallel Library is a set of APIs for parallel programming in .NET, used to improve performance by running tasks in parallel.



---

27. Normalization and ACID Properties

Normalization: The process of structuring a relational database to reduce redundancy and improve data integrity.

ACID:

A: Atomicity

C: Consistency

I: Isolation

D: Durability




---

28. Difference Between Dictionary and Hashtable

Answer:

Dictionary: Generic, type-safe, and faster. Dictionary<TKey, TValue>.

Hashtable: Non-generic and slower. It stores key-value pairs in object type.




---

29. Unit Testing in C#

Answer: Unit testing ensures individual units of code work as expected.

Example Using MSTest:

[TestMethod]
public void TestMethod()
{
    var result = Add(5, 3);
    Assert.AreEqual(8, result);
}



---

30. Dependency Injection in ASP.NET MVC

Answer: Dependency Injection can be achieved using Ninject or Unity frameworks.

Example:

IKernel kernel = new StandardKernel();
kernel.Bind<IMyService>().To<MyService>();
DependencyResolver.SetResolver(new NinjectDependencyResolver(kernel));



---

31. Get Employee Names from JSON

Example:

var employees = JsonConvert.DeserializeObject<List<Employee>>(jsonData);
var empNames = employees.Select(e => e.Name).ToList();



---

32. Spread Operator in JavaScript

Answer: The spread operator (...) allows an iterable to expand in places where 0+ arguments are expected.

Example:

let arr = [1, 2, 3];
let newArr = [...arr, 4, 5];  // [1, 2, 3, 4, 5]



---

33. Top 3 Employee Salaries SQL Query

SELECT TOP 3 Salary FROM Employees ORDER BY Salary DESC;


---

34. C# Program Output (Static Fields)

static String location; 
static DateTime time;

static void Main() {
    Console.WriteLine(location == null ? "location is null" : location); // Output: location is null
    Console.WriteLine(time == null ? "time is null" : time.ToString());  // Output: 1/1/0001 12:00:00 AM
}


---

35. C# Program Output (Record Type)

record Point(int X, int Y);
var original = new Point(1, 2);
var shifted = original with { X = original.X + 3, Y = original.Y - 1 };
Console.WriteLine(shifted); // Output: Point { X = 4, Y = 1 }


---

36. Tuples in C#

Answer: Tuples are a way to store multiple values in a single object.

Example:

var tuple = (1, "apple", true);
Console.WriteLine(tuple.Item1);  // Output: 1



---

37. Anonymous Methods in C#

Answer: Anonymous methods are inline unnamed methods used in place of delegate instances.

Example:

Func<int, int> square = delegate (int x) { return x * x; };
Console.WriteLine(square(5));  // Output: 25

#dotnettechpro #csharp #dotnet #dotnetdeveloper

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