What are Differences in Asp.net MVC 3, MVC 4 and MVC 5

Here are few differences:

• Razor view engine: ASP.NET MVC3 uses the ASPX view engine by default, while MVC4 and MVC5 introduced the Razor view engine, which is more concise and easier to read.

• Bundling and Minification: MVC4 introduced the new feature of bundling and minification, which makes it easier to combine and compress JavaScript and CSS files into a single file.

• Authentication filters: MVC5 introduced authentication filters that enable developers to apply authentication logic to controller actions or methods. This feature makes it easier to implement authentication logic in a modular and reusable way.

• Attribute routing: MVC5 introduced attribute routing, which provides a more intuitive and flexible way to define the URL routing rules. With attribute routing, you can define the route directly in the controller or action method, rather than in a central location.

• One ASP.NET: MVC5 introduced the concept of "One ASP.NET," which is a unified development model for web applications. It integrates ASP.NET MVC, Web API, and Web Pages into a single framework, making it easier to develop and maintain web applications.

• Bootstrap: MVC5 introduced support for Bootstrap, which is a popular front-end framework for building responsive web applications. With Bootstrap, you can quickly and easily create a modern and professional-looking user interface for your application.

• Filter overrides: MVC5 allows developers to override the filters defined in the global filter collection for a specific controller or action method. This feature makes it easier to customize the behavior of filters for specific parts of the application.

Overall, each version of ASP.NET MVC introduced new features and improvements that made it easier to develop web applications. As such, the latest version, MVC5, is generally the best choice for new projects, as it offers the most up-to-date feature

What is Delegate, Anonymous Method and Lambda Expression

A delegate is a type that represents a reference to a method with a specific signature. It is similar to a function pointer in C/C++. A delegate can be used to encapsulate a method call and pass it as an argument to another method or store it as a field or property. 

Here's an example:

public delegate int CalculationDelegate(int x, int y);

public class Calculator

{

    public int Add(int x, int y)

    {

        return x + y;

    }

    public int Multiply(int x, int y)

    {

        return x * y;

    }

}

public class Program

{

    public static void Main(string[] args)

    {

        Calculator calculator = new Calculator();

        CalculationDelegate add = calculator.Add;

        int result = add(2, 3); // result = 5

        CalculationDelegate multiply = calculator.Multiply;

        result = multiply(2, 3); // result = 6

    }

}

An anonymous method is a method without a name that can be defined inline with the code using a delegate. It allows you to define a method without having to create a separate method declaration. 

Here's an example:

CalculationDelegate add = delegate (int x, int y)

{

    return x + y;

};

int result = add(2, 3); // result = 5

A lambda expression is a concise way to define an anonymous method. It is a shorthand notation that allows you to define a method inline with the code using the => operator. Lambda expressions are typically used with delegates, but they can also be used with other types that define a single method, such as Func and Action. 

Here's an example:

CalculationDelegate add = (x, y) => x + y;

int result = add(2, 3); // result = 5

Lambda expressions are often used with LINQ queries, which use functional programming techniques to filter, sort, and transform data.

Why should We Use WCF Over Webservice

WCF (Windows Communication Foundation) is a more versatile and powerful technology than Web Services in .NET, and it offers several benefits over traditional Web Services. 

Here are some reasons why you might choose to use WCF over Web Services:

1. Flexibility: WCF provides a lot of flexibility in terms of communication protocols, message formats, and transport channels. WCF can communicate over HTTP, TCP, MSMQ, and other protocols, and it supports various message formats, including XML, JSON, and binary. This flexibility allows you to use WCF in a wide range of scenarios, from simple web services to complex distributed systems.
2. Interoperability: WCF is designed to be interoperable with other platforms and technologies. It supports standards-based protocols like SOAP, REST, and WS-* and can communicate with other systems regardless of the technology used. This makes it easier to integrate with legacy systems and other platforms.
3. Scalability: WCF is designed for scalability and performance. It supports various transport channels, including TCP and MSMQ, which are more scalable than HTTP. It also provides features like message streaming, message buffering, and throttling, which help optimize performance.
4. Security: WCF provides a comprehensive security model that supports various authentication and authorization mechanisms, such as SSL/TLS, username/password, and Windows authentication. It also supports message-level encryption and signing, which can ensure the confidentiality and integrity of messages.
5. Extensibility: WCF is highly extensible and customizable. It provides various extension points, such as behaviors, bindings, and contracts, which allow you to modify the behavior and functionality of the service to meet your specific requirements.

Overall, WCF is a more powerful and versatile technology than Web Services in .NET, and it offers several benefits over traditional Web Services. However, WCF also has a steeper learning curve and can be more complex to set up and configure, so it may not be the best choice for simple scenarios or small projects.

What is Difference in Static Class and Singleton

A static class and a singleton are two different design patterns in C# that are used for different purposes.

A static class is a class that can only contain static members (methods, properties, fields). It cannot be instantiated, and all its members are accessible through the class name itself. A static class is typically used to group related utility methods or constants that do not require any state or instance-specific behavior. 

Here's an example of a static class:

public static class Calculator

{

    public static int Add(int x, int y)

    {

        return x + y;

    }

    public static int Multiply(int x, int y)

    {

        return x * y;

    }

}

A singleton, on the other hand, is a class that can have only one instance throughout the lifetime of the application. It typically has a private constructor to prevent direct instantiation and provides a static method or property to access the singleton instance. A singleton is often used to represent a global state or to provide a centralized point of access to a resource or service. 

Here's an example of a singleton:

public class Logger

{

    private static Logger instance;

    private static readonly object lockObject = new object();

    private Logger()

    {

        // Private constructor to prevent direct instantiation

    }

    public static Logger Instance

    {

        get

        {

            // Double-checked locking to ensure thread-safety

            if (instance == null)

            {

                lock (lockObject)

                {

                    if (instance == null)

                    {

                        instance = new Logger();

                    }

                }

            }

            return instance;

        }

    }

    public void Log(string message)

    {

        // Logging implementation

    }

}

The main difference between a static class and a singleton is that a static class cannot be instantiated, whereas a singleton can have one instance. A static class is typically used to group related utility methods or constants, while a singleton is often used to represent a global state or to provide a centralized point of access to a resource or service.

What is Use of Static Constructor and When to Use it

A static constructor is a special type of constructor in C# that is used to initialize static data members or to perform any other type of static initialization. It is called automatically by the runtime before the first instance of the class is created or before any static members are accessed.

Here are some use cases for static constructors:

Initializing static data members

If you have static data members in your class that need to be initialized before they are used, you can use a static constructor to perform the initialization. This ensures that the static data members are initialized before any instance of the class is created or before any static members are accessed.

Registering event handlers 

If your class needs to register event handlers for static events, you can use a static constructor to perform the registration. This ensures that the event handlers are registered before any instance of the class is created or before any static members are accessed.

Setting up static configuration

If your class needs to read static configuration settings from a file or database, you can use a static constructor to perform the setup. This ensures that the configuration is read before any instance of the class is created or before any static members are accessed.

Performing other types of static initialization

If your class needs to perform any other type of static initialization, such as setting up a static cache or initializing a static database connection, you can use a static constructor to perform the initialization.

It's important to note that a static constructor is only called once, regardless of how many instances of the class are created or how many times static members are accessed. It is also called automatically by the runtime, so you don't need to explicitly call it in your code.

What is Difference in Temp Table and Table Variable

In SQL Server, a temporary table and a table variable are two different types of temporary storage objects that can be used to store data during the execution of a query or a batch.

Here are the main differences between temporary tables and table variables:

Scope

Temporary tables are created in the tempdb database and are visible to all sessions on the same SQL Server instance. Table variables are local to the batch or stored procedure in which they are defined.

Durability

Temporary tables are durable and are not dropped automatically when they go out of scope. You need to explicitly drop them when they are no longer needed. Table variables are not durable and are automatically dropped when they go out of scope.

Indexing

Temporary tables can have indexes and statistics, which can help improve query performance. Table variables do not support indexes, but they can benefit from statistics created on the columns used in queries against them.

Memory usage

Table variables are stored in memory, and their size is limited to the available memory on the server. Temporary tables can be stored in memory or on disk, depending on their size and the memory settings of the server.

Performance

Table variables are generally faster than temporary tables for small datasets, due to their in-memory storage and lack of indexing overhead. However, for larger datasets, temporary tables can be faster due to their ability to use indexes and statistics.

Here's an example of creating a temporary table:

CREATE TABLE #TempTable (

    ID INT PRIMARY KEY,

    Name VARCHAR(50)

);

INSERT INTO #TempTable (ID, Name)

VALUES (1, 'John'), (2, 'Jane'), (3, 'Bob');

SELECT * FROM #TempTable;

DROP TABLE #TempTable;

And here's an example of creating a table variable:

DECLARE @TableVariable TABLE (

    ID INT PRIMARY KEY,

    Name VARCHAR(50)

);

INSERT INTO @TableVariable (ID, Name)

VALUES (1, 'John'), (2, 'Jane'), (3, 'Bob');

SELECT * FROM @TableVariable;