.NET Interview Questions Part-3
53. Can you configure a .NET Remoting object via XML file?
Yes, via machine.config and application level .config file (or web.config in ASP.NET). Application-level XML settings take precedence over machine.config.
54. How can you automatically generate interface for the remotable object in .NET with Microsoft tools?
Use the Soapsuds tool.
55. What is Delegation?
A delegate acts like a strongly type function pointer. Delegates can invoke the methods that they reference without making explicit calls to those methods.
Delegate is an entity that is entrusted with the task of representation, assign or passing on information. In code sense, it means a Delegate is entrusted with a Method to report information back to it when a certain task (which the Method expects) is accomplished outside the Method's class.
56. What is "Microsoft Intermediate Language" (MSIL)?
A .NET programming language (C#, VB.NET, J# etc.) does not compile into executable code; instead it compiles into an intermediate code called Microsoft Intermediate Language (MSIL). As a programmer one need not worry about the syntax of MSIL - since our source code in automatically converted to MSIL. The MSIL code is then send to the CLR (Common Language Runtime) that converts the code to machine language, which is, then run on the host machine. MSIL is similar to Java Byte code. MSIL is the CPU-independent instruction set into which .NET Framework programs are compiled. It contains instructions for loading, storing, initializing, and calling methods on objects. Combined with metadata and the common type system, MSIL allows for true cross- language integration Prior to execution, MSIL is converted to machine code. It is not interpreted.
57. Differences between Datagrid, Datalist and Repeater?
1. Datagrid has paging while Datalist doesnt.
2. Datalist has a property called repeat. Direction = vertical/horizontal. (This is of great help in designing layouts). This is not there in Datagrid.
3. A repeater is used when more intimate control over html generation is required.
4. When only checkboxes/radiobuttons are repeatedly served then a checkboxlist or radiobuttonlist are used as they involve fewer overheads than a Datagrid.
The Repeater repeats a chunk of HTML you write, it has the least functionality of the three. DataList is the next step up from a Repeater; accept you have very little control over the HTML that the control renders. DataList is the first of the three controls that allow you Repeat-Columns horizontally or vertically. Finally, the DataGrid is the motherload. However, instead of working on a row-by-row basis, you’re working on a column-by-column basis. DataGrid caters to sorting and has basic paging for your disposal. Again you have little contro, over the HTML. NOTE: DataList and DataGrid both render as HTML tables by default. Out of the 3 controls, I use the Repeater the most due to its flexibility w/ HTML. Creating a Pagination scheme isn't that hard, so I rarely if ever use a DataGrid.
Occasionally I like using a DataList because it allows me to easily list out my records in rows of three for instance.
58. I am constantly writing the drawing procedures with System.Drawing.Graphics, but having to use the try and dispose blocks is too time-consuming with Graphics objects. Can I automate this?
Yes, the code
System.Drawing.Graphics canvas = new System.Drawing.Graphics();
try
{
//some code
}
finally
canvas.Dispose();
is functionally equivalent to
using (System.Drawing.Graphics canvas = new System.Drawing.Graphics())
{
//some code
} //canvas.Dispose() gets called automatically
59. How do you trigger the Paint event in System.Drawing?
Invalidate the current form, the OS will take care of repainting. The Update method forces the repaint.
60. With these events, why wouldn’t Microsoft combine Invalidate and Paint, so that you wouldn’t have to tell it to repaint, and then to force it to repaint?
Painting is the slowest thing the OS does, so usually telling it to repaint, but not forcing it allows for the process to take place in the background.
61. How can you assign an RGB color to a System.Drawing.Color object?
Call the static method FromArgb of this class and pass it the RGB values.
62. What class does Icon derive from? Isn’t it just a Bitmap with a wrapper name around it?
No, Icon lives in System.Drawing namespace. It’s not a Bitmap by default, and is treated separately by .NET. However, you can use ToBitmap method to get a valid Bitmap object from a valid Icon object.
63. Before in my VB app I would just load the icons from DLL. How can I load the icons provided by .NET dynamically?
By using System.Drawing.SystemIcons class, for example System.Drawing.SystemIcons.Warning produces an Icon with a warning sign in it.
64. When displaying fonts, what’s the difference between pixels, points and ems?
A pixel is the lowest-resolution dot the computer monitor supports. Its size depends on user’s settings and monitor size. A point is always 1/72 of an inch. An em is the number of pixels that it takes to display the letter M.
65. What is the difference between VB 6 and VB.NET?
Answer1
VB
1,Object-based Language
2,Doesnot support Threading
3,Not powerful Exception handling mechanism
4,Doesnot having support for the console based applications
5,Cannot use more than one version of com objects in vb application called DLL error
6,Doesnot support for the Disconnected data source.
VB.Net
1,Object-oriented Language
2,supports Threading
3,powerful Exception handling mechanism
4,having support for the console based applications
5,More than one version of dll is supported
6,supports the Disconnected data source by using Dataset class
Answer2
VB:
1. Object-based language
2. Does not support inheritance
3. ADO.Net does not give support for disconnected data architecture
4. No interoperability function
5. No support for threading
VB.Net
1. Object-Oriented Programming lanugage
2. ADO.Net gives support for disconnected data architecture
3. It provides interoperability
4. It uses managed code
5. supports threading
6. provides access to third-party controls like COM, DCOM
Answer2
1.The concept of the complete flow of execution of a program from start to finish: Visual Basic hides this aspect of programs from you, so that the only elements of a Visual Basic program you code are the event handlers and any methods in class modules. C# makes the complete program available to you as source code. The reason for this has to do with the fact that C# can be seen, philosophically, as next-generation C++. The roots of C++ go back to the 1960s and predate windowed user interfaces and sophisticated operating systems. C++ evolved as a low-level, closeto- the-machine, all-purpose language. To write GUI applications with C++ meant that you had to invoke the system calls to create and interact with the windowed forms. C# has been designed to build on this tradition while simplifying and modernizing C++, to combine the low-level performance benefits of C++ with the ease of coding in Visual Basic. Visual Basic, on the other hand, is designed specifically for rapid application development of Windows GUI applications. For this reason, in Visual Basic all the GUI boilerplate code is hidden, and all the Visual Basic programmer implements are the event handlers. In C# on the other hand, this boilerplate code is exposed as part of your source code.
2. Classes and inheritance: C# is a genuine object-oriented language, unlike Visual Basic, requiring all code to be a part of a class. It also includes extensive support for implementation inheritance. Indeed, most well-designed C# programs will be very much designed around this form of inheritance, which is completely absent in Visual Basic.
66. What are the authentication methods in .NET?
There are 4 types of authentications.
1.WINDOWS AUTHENTICATION
2.FORMS AUTHENTICATION
3.PASSPORT AUTHENTICATION
4.NONE/CUSTOM AUTHENTICATION
The authentication option for the ASP.NET application is specified by using the tag in the Web.config file, as shown below:
other authentication options
1. WINDOWS AUTHENTICATION Schemes
I. Integrated Windows authentication
II. Basic and basic with SSL authentication
III. Digest authentication
IV. Client Certificate authentication
2. FORMS AUTHENTICATION
You, as a Web application developer, are supposed to develop the Web page and authenticate the user by checking the provided user ID and password against some user database
3.PASSPORT AUTHENTICATION
A centralized service provided by Microsoft, offers a single logon point for clients. Unauthenticated users are redirected to the Passport site
4 NONE/CUSTOM AUTHENTICATION:
If we don’t want ASP.NET to perform any authentication, we can set the authentication mode to “none”. The reason behind this decision could be: We don’t want to authenticate our users, and our Web site is open for all to use. We want to provide our own custom authentication
67. What is Serialization in .NET?
Anwer1
The serialization is the process of converting the objects into stream of bytes.
they or used for transport the objects(via remoting) and persist objects(via files and databases)
Answer2
When developing smaller applications that do not have a database (or other formal storage mechanism) or data that doesn’t need to be stored in a database (such as the state of a web application), you often still would like to save the data for later retrieval. There are many ways to do this, but many of them are subject to a lot of extra code (work) and extra time spent debugging. With .NET, there is now an easy way to add this functionality to your code with only a few lines of easily tested code. This easy way is called serialization.
Serialization is the process of storing an object, including all of its public and private fields, to a stream. Deserialization is the opposite – restoring an object’s field values from a stream. The stream is generally in the form of a FileStream, but does not have to be. It could be a memory stream or any other object that is of type IO.Stream. The format can be anything from XML to binary to SOAP.
68. What’s the use of System.Diagnostics.Process class?
By using System.Diagnostics.Process class, we can provide access to the files which are presented in the local and remote system.
Example: System.Diagnostics.Process(”c:\mlaks\example.txt”) — local file
System.Diagnostics.Process(”http://www.mlaks.com\example.txt”) — remote file
69. Difference Abstract class and Interface
Abstract class: This class has abstract methods (no body). This class cannot be instantiated. One needs to provide the implementation of the methods by overriding them in the derived class. No Multiple Inheritance.
Interfaces: Interface class contains all abstract methods which are public by default. All of these methods must be implemented in the derived class. One can inherit from from more than one interface thus provides for Multiple Inheritance.
70. re-clarification of object based:
VB6 DOES support polymorphism and interface inheritance. It also supports the “Implements” keyword. What is not supported in vb6 is implementation inheritance.
Also, from above, vb6 DOES “provides access to third-party controls like COM, DCOM ” That is not anything new in .NET.
71. How to achieve Polymorphism in VB.Net?
We can achieve polymarphism in .Net i.e Compile time polymarphism and Runtime polymarphism. Compiletime Polymarphism achieved by method overloading. Runtime polymarphism achieved by Early Binding or Late Binding. Provide the function pointer to the object at compile time called as Early Binding.
provide the function pointer to the object at runtime called as Late Binding
class emp having the method display()
class dept having the method display()
create objects as in the main function
// Early binding
dim obj as new emp
dim ob as new dept
obj.display()-to call the display method of emp class
ob.display-to call the display method of the dept class
// Late binding
create object in the main class as
object obj
obj=new emp
obj.display()-to call the display of emp class
obj=new dept
obj.display()-to call the display of dept class
72. Difference between Class And Interface
Class is logical representation of object. It is collection of data and related sub procedures with defination.
Interface is also a class containg methods which is not having any definations.
Class does not support multiple inheritance. But interface can support.
73. What doesu mean by .NET framework?
The .NET Framework is an environment for building, deploying, and running Web Services and other applications. It consists of three main parts: the Common Language Runtime, the Framework classes, and ASP.NET
74. What is assembly?
It is a single deployable unit that contains all the information abt the implimentation of classes , stuctures and interfaces
75. What is namespaces?
It is a logical group of related classes and interfaces and that can be used byany language targeting the .net framework.
.NET framework programming interview questions
.NET framework overview
1. Has own class libraries. System is the main namespace and all other namespaces are subsets of this.
2. It has CLR(Common language runtime, Common type system, common language specification)
3. All the types are part of CTS and Object is the base class for all the types.
4. If a language said to be .net complaint, it should be compatible with CTS and CLS.
5. All the code compiled into an intermediate language by the .Net language compiler, which is nothing but an assembly.
6. During runtime, JIT of CLR picks the IL code and converts into PE machine code and from there it processes the request.
7. CTS, CLS, CLR
8. Garbage Collection
9. Dispose, finalize, suppress finalize, Idispose interface
10. Assemblies, Namespace: Assembly is a collection of class/namespaces. An assembly contains Manifest, Metadata, Resource files, IL code
11. Com interoperability, adding references, web references
12. Database connectivity and providers
Application Domain
1. Class modifiers: public, private, friend, protected, protected friend, mustinherit, NotInheritable
2. Method modifiers: public, private
3. Overridable
4. Shadows
5. Overloadable
6. Overrides
7. Overloads
8. Set/Get Property
9. IIF
10. Inheritance
11. Polymorphism
12. Delegates
13. Events
14. Reflection
15. Boxing
16. UnBoxing
ASP.Net
1. Web Controls: Data grid (templates, sorting, paging, bound columns, unbound columns, data binding), Data list, repeater controls
2. HTML Controls
3. Code behind pages, system.web.ui.page base class
4. Web.config: App settings, identity (impersonate), authentication (windows, forms, anonymous, passport), authorization
5. Databind.eval
6. Trace, Debug
7. Output cache
8. Session management
9. Application, Session
10. Global.asax httpapplication
11. User controls, custom controls, custom rendered controls (postback event, postdatachanged event) usercontrol is the base class
12. Directives
ADO.Net
1. Command object (ExecuteNonquery, ExecuteReader, ExecuteXMLReader, ExecuteScalar)
2. DataAdapter object (Fill)
3. Dataset (collection of tables)
4. CommandBuiler object
5. Transaction Object
6. Isolation levels