Difference between array, arraylist, List, Hashtable, Dictionary and SortedList in c#

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Basic difference is that arrays are of fixed size. Whereas an ArrayList implements the list data structure and can dynamically grow. While arrays would be more performance that a list, a list would be far more flexible since you don't need to know the required size initially. Array - represents an old-school memory array - kind of like a alias for a normal type[] array. Can enumerate. Can't grow automatically. I would assume very fast insertion, retrieve and speed. ArrayList - automatically growing array. Adds more overhead. Can enum., probably slower than a normal array but still pretty fast. These are used a lot in .NET List - one of my favorites - can be used with generics, so you can have a strongly typed array, e.g. List . Other than that, acts very much like ArrayList. Hashtable - plain old hashtable. O(1) to O(n) worst case. Can enumerate the value and keys properties, and do key/val pairs. Dictionary - same as above only strongly typed via generics, such a...
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ASP.NET MVC Interview Question with answer Part 1

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What is MVC (Model View Controller)?

MVC is an architectural pattern which separates the representation and user interaction. It’s divided into three broader sections, Model, View, and Controller. Below is how each one of them handles the task.
  • The View is responsible for the look and feel.
  • Model represents the real world object and provides data to the View.
  • The Controller is responsible for taking the end user request and loading the appropriate Model and View.

Figure: MVC (Model view controller)

Explain MVC application life cycle?

There are six broader events which occur in MVC application life cycle below diagrams summarize it.


Any web application has two main execution steps first understanding the request and depending on the type of the request sending out appropriate response. MVC application life cycle is not different it has two main phases first creating the request object and second sending our response to the browser.
Creating the request object: -The request object creation has four major steps. Below is the detail explanation of the same.
Step 1 Fill route: - MVC requests are mapped to route tables which in turn specify which controller and action to be invoked. So if the request is the first request the first thing is to fill the route table with routes collection. This filling of route table happens in the global.asax file.
Step 2 Fetch route: - Depending on the URL sent “UrlRoutingModule” searches the route table to create “RouteData” object which has the details of which controller and action to invoke.
Step 3 Request context created: - The “RouteData” object is used to create the “RequestContext” object.
Step 4 Controller instance created: - This request object is sent to “MvcHandler” instance to create the controller class instance. Once the controller class object is created it calls the “Execute” method of the controller class.
Creating Response object: - This phase has two steps executing the action and finally sending the response as a result to the view.

Is MVC suitable for both Windows and Web applications?

The MVC architecture is suited for a web application than Windows. For Window applications, MVP, i.e., “Model View Presenter” is more applicable. If you are using WPF and Silverlight, MVVM is more suitable due to bindings.

What are the benefits of using MVC?

There are two big benefits of MVC:
  • Separation of concerns is achieved as we are moving the code-behind to a separate class file. By moving the binding code to a separate class file we can reuse the code to a great extent.
  • Automated UI testing is possible because now the behind code (UI interaction code) has moved to a simple .NET class. This gives us opportunity to write unit tests and automate manual testing.

Is MVC different from a three layered architecture?

MVC is an evolution of a three layered traditional architecture. Many components of the three layered architecture are part of MVC. So below is how the mapping goes:

Functionality Three layered / tiered architecture Model view controller architecture
Look and Feel User interface View
UI logic User interface Controller
Business logic /validations Middle layer Model
Request is first sent to User interface Controller
Accessing data Data access layer Data Access Layer


Figure: Three layered architecture

What is the latest version of MVC?

MVC 6 is the latest version which is also termed as ASP VNEXT.

What is the difference between each version of MVC 2, 3 , 4, 5 and 6?

MVC 6
ASP.NET MVC and Web API has been merged in to one.
Dependency injection is inbuilt and part of MVC.
Side by side - deploy the runtime and framework with your application
Everything packaged with NuGet, Including the .NET runtime itself.
New JSON based project structure.
No need to recompile for every change. Just hit save and refresh the browser.
Compilation done with the new Roslyn real-time compiler.
vNext is Open Source via the .NET Foundation and is taking public contributions.
vNext (and Rosyln) also runs on Mono, on both Mac and Linux today.

MVC 5
One ASP.NET
Attribute based routing
Asp.Net Identity
Bootstrap in the MVC template
Authentication Filters
Filter overrides

MVC 4
ASP.NET Web API
Refreshed and modernized default project templates
New mobile project template
Many new features to support mobile apps
Enhanced support for asynchronous methods

MVC 3
Razor
Readymade project templates
HTML 5 enabled templates
Support for Multiple View Engines
JavaScript and Ajax
Model Validation Improvements

MVC 2
Client-Side Validation
Templated Helpers
Areas
Asynchronous Controllers
Html.ValidationSummary Helper Method
DefaultValueAttribute in Action-Method Parameters
Binding Binary Data with Model Binders
DataAnnotations Attributes
Model-Validator Providers
New RequireHttpsAttribute Action Filter
Templated Helpers
Display Model-Level Errors

What are HTML helpers in MVC?

HTML helpers help you to render HTML controls in the view. For instance if you want to display a HTML textbox on the view , below is the HTML helper code.
<%= Html.TextBox("LastName") %>
For checkbox below is the HTML helper code. In this way we have HTML helper methods for every HTML control that exists.
 
<%= Html.CheckBox("Married") %>

What is the difference between “HTML.TextBox” vs “HTML.TextBoxFor”?

Both of them provide the same HTML output, “HTML.TextBoxFor” is strongly typed while “HTML.TextBox” isn’t. Below is a simple HTML code which just creates a simple textbox with “CustomerCode” as name.
Html.TextBox("CustomerCode")
 
Below is “Html.TextBoxFor” code which creates HTML textbox using the property name ‘CustomerCode” from object “m”.
Html.TextBoxFor(m => m.CustomerCode)
 
In the same way we have for other HTML controls like for checkbox we have “Html.CheckBox” and “Html.CheckBoxFor”.

What is routing in MVC?

Routing helps you to define a URL structure and map the URL with the controller.
For instance let’s say we want that when a user types “http://localhost/View/ViewCustomer/”, it goes to the “Customer” Controller and invokes the DisplayCustomer action. This is defined by adding an entry in to the routes collection using the maproute function. Below is the underlined code which shows how the URL structure and mapping with controller and action is defined.
routes.MapRoute(
               "View", // Route name
               "View/ViewCustomer/{id}", // URL with parameters
               new { controller = "Customer", action = "DisplayCustomer", 
id = UrlParameter.Optional }); // Parameter defaults

Where is the route mapping code written?

The route mapping code is written in "RouteConfig.cs" file and registered using "global.asax" application start event.

Can we map multiple URL’s to the same action?

Yes, you can, you just need to make two entries with different key names and specify the same controller and action.

Explain attribute based routing in MVC?

This is a feature introduced in MVC 5. By using the "Route" attribute we can define the URL structure. For example in the below code we have decorated the "GotoAbout" action with the route attribute. The route attribute says that the "GotoAbout" can be invoked using the URL structure "Users/about".
public class HomeController : Controller
{
       [Route("Users/about")]
       public ActionResult GotoAbout()
       {
           return View();
       }
}

What is the advantage of defining route structures in the code?

Most of the time developers code in the action methods. Developers can see the URL structure right upfront rather than going to the “routeconfig.cs” and see the lengthy codes. For instance in the below code the developer can see right upfront that the “GotoAbout” action can be invoked by four different URL structure.
This is much user friendly as compared to scrolling through the “routeconfig.cs” file and going through the length line of code to figure out which URL structure is mapped to which action.
public class HomeController : Controller
{
       [Route("Users/about")]
       [Route("Users/WhoareWe")]
       [Route("Users/OurTeam")]
       [Route("Users/aboutCompany")]
       public ActionResult GotoAbout()
       {
           return View();
       }
}

How can we navigate from one view to another using a hyperlink?

By using the ActionLink method as shown in the below code. The below code will create a simple URL which helps to navigate to the “Home” controller and invoke the GotoHome action.
<%= Html.ActionLink("Home","Gotohome") %>

How can we restrict MVC actions to be invoked only by GET or POST?

We can decorate the MVC action with the HttpGet or HttpPost attribute to restrict the type of HTTP calls. For instance you can see in the below code snippet the DisplayCustomer action can only be invoked by HttpGet. If we try to make HTTP POST on DisplayCustomer, it will throw an error.
[HttpGet]
public ViewResult DisplayCustomer(int id)
{
    Customer objCustomer = Customers[id];
    return View("DisplayCustomer",objCustomer);
}

How can we maintain sessions in MVC?

Sessions can be maintained in MVC by three ways: tempdata, viewdata, and viewbag.

What is the difference between tempdata, viewdata, and viewbag?


Figure: Difference between tempdata, viewdata, and viewbag
  • Temp data - Helps to maintain data when you move from one controller to another controller or from one action to another action. In other words when you redirect, tempdata helps to maintain data between those redirects. It internally uses session variables.
  • View data - Helps to maintain data when you move from controller to view.
  • View Bag - It’s a dynamic wrapper around view data. When you use Viewbag type, casting is not required. It uses the dynamic keyword internally.

Figure: dynamic keyword
  • Session variables - By using session variables we can maintain data from any entity to any entity.
  • Hidden fields and HTML controls - Helps to maintain data from UI to controller only. So you can send data from HTML controls or hidden fields to the controller using POST or GET HTTP methods.
Below is a summary table which shows the different mechanisms for persistence.
Maintains data between ViewData/ViewBag TempData Hidden fields Session
Controller to Controller No Yes No Yes
Controller to View Yes No No Yes
View to Controller No No Yes Yes

Source : Code project

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