Tuesday, November 11, 2008
OOPS:
1) What is OOPs?
OOPs - Object Oriented Programming Languages & Systems
Everything in the world is an object. The type of the object may vary. In OOPS, we get the power to create objects of our own, as & when required. OOPs is a programming methodology where each entity is an object.
It is a method of computer programming where entities of related data together with routines associated with it are treated as one object in the program.
2) What is a class? What is a Base Class?
A class is an organized store-house in object-oriented programming that gives coherent functional abilities to a group of related code. It is the definition of an object, made up of software code. Using classes, we may wrap data and behaviour together (Encapsulation). We may define classes in terms of classes (Inheritance). We can also override the behaviour of a class using an alternate behaviour (Polymorphism).
It is important to note that a class is a Reference Type. To know about Reference Types, Click Here
A Base Class is a class that is inherited by another class. In .NET, a class may inherit from only one class.
3) What is Encapsulation?
Encapsulation - is the ability of an object to hide its data and methods from the rest of the world. It is one of the fundamental principles of OOPs.
Say we create a class, named Calculations. This class may contain a few members in the form of properties, events, fields or methods. Once the class is created, we may instantiate the class by creating an object out of it. The object acts as an instance of this class, the members of the class are not exposed to the outer world directly, rather, they are encapsulated by the class.
Example:
Public class Calculations
{
private void fnMultiply(int x, int y)
{
return x * y;
}
}
...
...
Calculations obj;
int Result;
Result = obj.fnMultiply(5,10);
4) What is inheritance?
Inheritance - is the concept of passing the traits of a class to another class.
A class comprises of a collection of types of encapsulated instance variables and types of methods, events, properties, possibly with implementation of those types together with a constructor function that can be used to create objects of the class. A class is a cohesive package that comprises of a particular kind of compile-time metadata. A Class describes the rules by which objects behave; these objects are referred to as "instances" of that class. (Reference)
Classes can inherit from another class. This is accomplished by putting a colon after the class name when declaring the class, and naming the class to inherit from—the base class—after the colon. (Reference)
5) What is a class member? What is an object?
The entities like events, properties, fields and functions encapsulated within a class are called class members. A constructor of a class that resides within it is also a form of a class member.
When we instantiate a class in order to use its encapsulated class members, this instantiated class entity is called the object.
6) What is polymorphism?
Polymorphism means allowing a single definition to be used with different types of data (specifically, different classes of objects). For example, a polymorphic function definition can replace several type-specific ones, and a single polymorphic operator can act in expressions of various types. Many programming languages implement some forms of polymorphism.
The concept of polymorphism applies to data types in addition to functions. A function that can evaluate to and be applied to values of different types is known as a polymorphic function. A data type that contains elements of different types is known as a polymorphic data type.
Polymorphism may be achieved by overloading a function, overloading an operator, changing the order of types, changing the types using the same name for the member in context.
Example:
Public Class Calc
{
public void fnMultiply(int x, int y)
{ return x * y; }
public void fnMultiply(int x, int y, int z)
{ return x * y * z; }
}
...
...
Calc obj;
int Result;
Result = obj.fnMultiply(2,3,4); // The second fnMultiply would be called
Result = obj.fnMultiply(3,4); // The first fnMultiply would be called
//Here, the call depends on the number of parameters passed, polymorphism is achieved using overloading
7) What is a property? What is an event?
Property - A property is a thing that describes the features of an object. A property is a piece of data contained within a class that has an exposed interface for reading/writing. Looking at this definition, we might think we could declare a public variable in a class and call it a property. While this assumption is somewhat valid, the real technical term for a public variable in a class is a field. The main difference between a field and a property is in the inclusion of an interface.
We make use of Get and Set keywords while working with properties. We prefix the variables used within this code block with an underscore. Value is a keyword, that holds the value which is being retrieved or set.ss="a">
Private _Color As String
Public Property Color()
Get
Return _Color
End Get
Set(ByVal Value)
_Color = Value
End Set
End Property
Event - An action that an object does. When something happens, we say an event has happened. For example, when a button is clicked, we say it is the click( ) event. When a mouse hovers on an image, we say the mouseover( ) event has taken place.
8) What is an access modifier? What are the different types of Access modifiers?
Access Modifiers - Keywords used to change the way members of a class are accessed. The main purpose of using access specifiers is to provide security to the applications. The availability (scope) of the member objects of a class may be controlled using access specifiers.
9) What is Overloading? What is Overloads? What is Overload?
Overloading - is the concept of using one function or class in different ways by changing the signature of its parameters. We can define a function with multiple signatures without using the keyword Overloads, but if you use the Overloads keyword in one, you must use it in all of the function's Overloaded signatures.
The Overloads keyword is used in VB.NET, while the Overload keyword is used in C# (There is no other difference). The Overloads property allows a function to be described using deferent combinations of parameters. Each combination is considered a signature, thereby uniquely defining an instance of the method being defined.
Overloading is a way through which polymorphism is achieved.
10) What is shared keyword used for? What is static?
Shared and Static mean the same. Shared is used in VB.NET, while Static is used in C#.
11) What is the virtual keyword used for?
Virtual - If a base class method is to be overriden, it is defined using the keyword virtual (otherwise the sealed keyword is used to prevent overriding).
Note that the class member method may be overriden even if the virtual keyword is not used, but its usage makes the code more transparent & meaningful. In VB.NET, we may use the overridable keyword for this purpose.
When the override keyword is used to override the virtual method, in a scenario where the base class method is required in a child class along with the overriden method, then the base keyword may be used to access the parent class member. The following code example will make the usage more clear.
public class Employee
{
public virtual void SetBasic(float money) //This method may be overriden
{ Basic += money; }
}
public class Manager : Employee
{
public override void SetBasic(float money) //This method is being overriden
{
float managerIncentive = 10000;
base.SetSalary(money + managerIncentive); //Calling base class method
}
}
12) Explain overridable, overrides, notoverridable,mustoverride
These keywords are used in VB.NET.
Overridable -The Overridable keyword is used when defining a property or method of an inherited class, as overridable by the inheriting class.
Overides - The Overides keyword allows the inheriting class to disregard the property or method of the inherited class and implements ts own code.
NotOverridable - The NotOverridable keyword explicitly declares a property or method as not overridable by an inheriting class, and all properties are "not overridable" by default. The only real advantage to using this keyword is to make your code more readable.
MustOverride - The MustOverride keyword forces the inheriting class to implement its own code for the property or method.
13) What is shadowing? Explain shadows keyword
Shadowing - is a concept of altering the behavior of a base class member.
14) What is a constructor? Explain the New Keyword. What is a Private Constructor?
Constructor - A constructor is a function with the same name as that of the class. The Default Constructor of a class is without an argument. The default constructor ensures that every member data is initialized to a default value. Constructors provide a way for classes to initialize a state for their members. Note that constructors dont have a return type(not even void).
public SomeClass()
{
Console.Writeline("Vishal says, Default Constructor is called");
}
\
public SomeClass(string str)
{
Console.Writeline("Vishal says, Custom Constructor is called" + str);
}
When a custom constructor is defined, the Default Constructor is not called. A constructor may also be overloaded.
New - This keyword may be used as a modifier and as an operator. When used as an operator, it creates an object on a heap to invoke constructors. When used an a modifier, it hides an inherited member from the base class member.
As an operator, it can be used to create an object and then to invoke the constructor of the class. See example below.
Example
SomeClass objSomeClass = new SomeClass(); //Creating a class object and invoking its constructor
float amount = new float(); //Creating an object of the type, and invoking its constructor
As a modifier, it is used to explicitly hide a member from the base class. See example.
Example
public class MamaClass
{
public void SomeMethod() { ... }
}
public class BabyClass : MamaClass
{
new public void SomeMethod() { .... }
}
Private Constructor - When a constructor is created with a private specifier, it is not possible for other classes to derive from this class, neither is it possible to create an instance of this class. They are usually used in classes that contain static members only. It is also used to create Singleton classes.
15) What is a static constructor?
Static Constructor - It is a special type of constructor, introduced with C#. It gets called before the creation of the first object of a class(probably at the time of loading an assembly). See example below.
Example:
public class SomeClass()
{
static SomeClass()
{
//Static members may be accessed from here
//Code for Initialization
}
}
While creating a static constructor, a few things need to be kept in mind:
* There is no access modifier require to define a static constructor
* There may be only one static constructor in a class
* The static constructor may not have any parameters
* This constructor may only access the static members of the class
* We may create more than one static constructor for a class
Can a class be created without a constructor?
No. In case we dont define the constructor, the class will access the no-argument constructor from its base class. The compiler will make this happen during compilation.
16) What is Serialization? What is serializable attribute used for?
Serialization - The process of converting an object into a stream of bytes. This stream of bytes can be persisted. Deserialization is an opposite process, which involves converting a stream of bytes into an object. Serialization is used usually during remoting (while transporting objects) and to persist file objecst & database objects.
.NET provides 2 ways for serializtion 1) XmlSerializer and 2) BinaryFormatter/SoapFormatter
The XmlSerializer is used for Web Services. The BinaryFormatter & SoapFormatter is used for Remoting. While using XmlSerializer, it is required that the target class has parameter less constructors, has public read-write properties and has fields that can be serialized. The XmlSerializer has good support for XML documents. It can be used to construct objects from existing XML documents. The XmlSerializer enables us to serialize and deserialize objects to an XML format.
SoapFormatter enables us to serialize & deserialize objects to SOAP format. They can serialize private and public fields of a class. The target class must be marked with the Serializable attribute. On deserialization, the constructor of the new object is not invoked.
The BinaryFormatter has the same features as the SoapFormatter except that it formats data into binary format. The BinaryForamatter (and the SoapFormatter) has two main methods. Serialize and Deserialize. To serialize an object, we pass an instance of the stream and the object to the Serialize method. To Deserialize an object, you pass an instance of a stream to the Deserialize method.
You can use the BinaryFormatter to serialize many, but not all, classes in the .NET Framework. For example, you can serialize ArrayLists, DataSets, and Arrays but not other objects, such as DataReaders or TextBox controls. To serialize a class, the class must have the Serializable attribute or implement the ISerializable interface.
Note that the XmlSerializer captures only the public members of the class, whereas the BinaryFormatter & the SoapFormatter captures both the public & private members of the class. The output using the BinaryFormatter is quite compact, as the information is in binary format, whereas the XmlSerializer format is filled with XML tags. See example below...
Imports System.IOImports System.Runtime.Serialization.Formatters.Binary
Dim colArrayList As ArrayListDim
objFileStream As FileStreamDim
objBinaryFormatter As BinaryFormattercolArrayList = New ArrayList()
colArrayList.Add( "Whisky")
colArrayList.Add( "Vodka")
colArrayList.Add( "Brandy")
objFileStream = New FileStream(MapPath("C:\myArrayList.data"), FileMode.Create)
objBinaryFormatter = New BinaryFormatterobjBinaryFormatter.Serialize(objFileStream, colArrayList)objFileStream.Close()
Here we see that an instance of the file stream (objFileStream) and an instance of the object (colArrayList) is passed to the Serialize method of the BinaryFormatter object (objBinaryFormatter). We also end up creating a file by the name myArrayList.data on our hard-drive.In order to deserialize an object, see the code below…
Dim colArrayList As ArrayListDim objFileStream As FileStreamDim
objBinaryFormatter As BinaryFormatterDim strItem As String
objFileStream = New FileStream( MapPath("myArrayList.data"), FileMode.Open )
objBinaryFormatter = New BinaryFormatter
colArrayList = CType( objBinaryFormatter.Deserialize( objFileStream ), ArrayList )
objFileStream.Close()
For Each strItem In colArrayList
Response.Write( " " & strItem )
Next
Here, CType takes in two parameters, the first parameter is the serialized object in the file stream format, and the second parameter is the desired type. Finally, the page iterates through all the elements of the ArrayList and displays the value of each element.
XmlSerializer does not serialize instances of classes like Hashtable which implement the IDictionary interface.
Serializable - This is a class attribute. When we use this attribute with a class, an instance of this class can be taken in whatever state it is, and write it to a disk. The class can then be deserialized, and the class will act as if it is simply stored in the memory.
17) What is a delegate? What is a Multicast Delegate?
Delegate - It is a type safe function pointer. It is a type that holds the reference of a method. A delegate may be used to call a method asynchronously.
Multicast Delegate - it is a delegate that holds reference of more than one method. Multicast Delegates must have a return type of void.
18) What is an abstract class?
If a class is to serve the purpose of providing common fields and members to all subclasses, we create an Abstract class. For creating an abstract class, we make use of the abstract keyword. Such a class cannot be instantiated.
19) What is an interface? How to implement an interface?
An Interface is a collection of semantically related abstract members. An interface expresses through the members it defines, the behaviors that a class needs to support. An interface is defined using the keyword interface. The members defined in an interface contain only definition, no implementation. The members of an interface are all public by default, any other access specifier cannot be used.
An interface is implemented using implements keyword. A class may implement more than one keyword.
When a class inherits and implements at the same time, the inherited parent class name is written first, followed by the names of the interfaces to be implemented
20) Is multiple inheritance possible in .NET?
No. Multiple inheritance is not possible in .NET. This means it is not possible for one class to inherit from multiple classes. However, a class may implement multiple interfaces. We may also declare objects of different classes in a class. This way, the encapsulated class may be instantiated in other classes.
ASP.NET 2.0
1) Can we bind data to a server control without writing code in .NET?
Yes, that is possible. ASP.NET 2.0 has the feature of declarative solution for data binding which requires no code at all for the most common data scenarios, such as:
* Selecting and displaying
* Data Sorting
* Paging and Caching
* Data Updating
* Inserting and Deleting Data
2) How to use Masterpages and Contentpages in ASP.NET 2.0? What is a Masterpage? What is a ContentPage? How to setup master-content pages in ASP.NET 2.0?
A Master Page is the mother of the page and the content page is the baby! There may be many babies of the mother. A master page may have plenty of content pages within it. There also may be a master page within a master page, which is called a nested master page. Nested Master Pages
So whats a master page in ASP.NET 2.0? A Master Page is a page that contains markup and controls that are shared across multiple pages in your site. For example, if required that all pages should have the same header and footer banners or the common navigation menu, the Master page can be written once, and all the content pages can access the common master page. The content pages inherit the tags inside the master page.
Next question is how to define a master page. The answer is...
To define a Master Page, it may be written like a normal page. Master Pages can contain markup, controls, or code, or any combination of these tags. The Content pages are rendered in a master page control called as ContentPlaceHolder control. A ContentPlaceHolder defines a region of the master page rendering that can be exchanged with content from a page associated to the master. A ContentPlaceHolder can also contain default content, when in case the derive page does not need to override this content. Below is the markup of how to use a Contentplaceholder.
Welcome to the .NET Interview Questions website!
A master page has the extension .master, unlike a normal web form that has the extenstion .aspx. A page may derive from a Master Page by defining a MasterPageFile attribute on its Page directive. Below is the markup of a content page.
<%@ Page MasterPageFile="Masterpage.master" %>
Here goes contents of ContentPlaceHolderInterviewQuestions
So how does Content page access a master page? It is also possible for a Content Page to programmatically access a Master Page. A ContentPage may create a strongly-typed reference to the Master Page using the <%@ MasterType %> directive, which specifies the virtual path to the masterpage as below...
<%@ MasterType VirtualPath="Masterpage.master" %>
The Content Page may then reference the Master Page using the Master property of the Page class:
Master.FooterText = "Some text on the footer of .NET Interview Questions page";
Label lb1 = Master.FindControl("label2");
As with the example above, FooterText is a public property exposed on the Master Page, whereas label2 is a server side control on the Master Page.
Note that the FindControl method is a very useful and a very important method, that may be used for finding a control in a content page from a master page and vice versa.
3) What is a nested Masterpage in ASP.NET 2.0? Can there be a master page inside a masterpage?
When a master page is placed inside the contentplaceholder of a masterpage, then the masterpage is said to be nested. In other words, there is one parent masterpage, and the child masterpage is inside the contentplaceholder of the parent masterpage.
Yes, we can have multiple number of Master pages in an ASP.NET 2.0 web application.
4) What is a SiteMapPath control in ASP.NET 2.0?
An asp:SiteMapPath control is a Navigation Control that comes along with the ASP.NET 2.0 framework. The sitemappath control consists site link's data in XML format. The emergence of the Sitemappath control in ASP.NET 2.0 has totally eliminated the clumsy code used in bread crumbs by veteran web developers in Classic ASP and ASP.NET 1.1. These bread crumbs were comparatively tougher to maintain.
Now say you need to maintain a Sitemap of a Site having the following links...
Home Products Medicines Soaps Alcohol Support Phone Support Email Support Contact Us
Instead of hard coding these links inside your code, all this information may be maintained in an XML based Web.sitemap file which can be bind to an asp:SiteMapPath control, and this would display like a website breadcrumb. Easier than before!
The SiteMapPath control's SiteMapProvider property is used to set the site's sitemap provider. This sitemap provider is another control called asp:XmlDataSource control. This needs to be registered in the web.config file. If the SiteMapProvider property is not specified, then the default SiteMap Provider information is picked up from the web.config file.
Note:The other two navigation controls in ASP.NET 2 are the Menu control and the TreeView control.
The XmlDataSource control loads an XML file that is specified using the DataFile property. This control inherits from the HierarchicalDataSourceControl class.
Example XML below:
If DataFile is not used in the XmlDataSource, the siteMapFile property can be set in the web.config.
In order to specify XML Data Source in web.config, see below:
5) How to sort the contents of a GridView control?
The ASP.NET 2.0 GridView control is a powerful control, the enables sorting of the rows based on a column, all this possible, without writing code. Well thats what we call power!
The GridView control relies on the underlying data source control to whom this is bound for the sorting capability. The GridView needs to have an AccessDataSource or an SQlDataSource or an ObjectDataSource (if the SortParameterName property is set to a value allowed.
The AllowSorting property of the GridView control, when set to true, enables sorting of the GridView. A sortable GridView has the Header column represented as a LinkButton control. When this Link Button is clicked, the Sorting event of the GridView is raised server-side, which causes a postback and in turn, sorts the GridView control's records.
6) What does the Hotspot class in .NET do? What is an ImageMap in ASP.NET?
An ImageMap is an ASP.NET control that allows clicks inside a polygon like (called Hotspot) region in a webpage. Well, that actually means you may create a star-shaped or diamond shaped button. Wow!
There are several pre-defined shapes allowed inside an ImageMap for which templates may be used. For example, for a rectangle, an asp:RectangularHotSpot may be used. For a circle, an asp:CircleHotSpot may be used. And for creating stars & diamonds, an asp:PolygonHotSpot may be used. An image may also be put in an ImageMap which may be specified by its ImageUrl property.
In order to invoke an event, the HotSpotMode property needs to be set to PostBack. Further, if several HotSpots are placed inside an ImageMap, the event of the ImageMap may be passed a value using the PostBackValue property.
Code below shows how to create a Polygon HotSpot using an ImageMap.
AlternateText="Click Here"
HotSpotMode="Navigate">
Coordinates="100,150, 250,350, 210,290, 90,350, 60,240"
NavigateUrl="http://www.asp.net"
Target="_blank"/>
7) How do we update and delete data in a gridview? Datakeynames property in .NET?
The best way to Update or Delete a record in a GridView control is to include a CheckBox column and a Submit Button.
The GridView has its own Delete and Edit functionality. If the GridView is populated with data using an SqlDataSource, checkout the wizard that comes along with the SqlDataSource. It may be used to automatically create an SQL Delete command and specify the delete parameters.
The DataKeyNames property of the GridView is set to a field name of the Table.
Follow these links for a detailed understanding of the various ways a GridView record may be updated & deleted.
AspAlliance
EggHeadCafe
ASP.NET QuickStart
MSDN
CodeProject
SqlConnection (.NET)
Standard Security:
"Data Source=UrServerName;
Initial Catalog=pubs;
User Id=myUsername;
Password=myPassword;"
OR
"Server=UrServerName;
Database=pubs;
User ID=myUsername;
Password=myPassword;
Trusted_Connection=False"
Trusted Connection:
"Data Source=UrServerName;
Initial Catalog=pubs;
Integrated Security=SSPI;"
OR
"Server=UrServerName;
Database=pubs;
Trusted_Connection=True;"
(Note: use serverName\instanceName as Data Source to use
an specifik SQLServer instance)
Connect via an IP address:
"Data Source=190.190.200.100,1433;
Network Library=DBMSSOCN;
Initial Catalog=pubs;
User ID=myUsername;
Password=myPassword;"
(Note: DBMSSOCN=TCP/IP instead of Named Pipes,
at the end of the Data Source is the port to use (1433
is the default))
Enabling MARS (multiple active result sets):
"Server=UrServerName;
Database=pubs;
Trusted_Connection=True;
MultipleActiveResultSets=true"
Note- Use ADO.NET 2.0 for MARS functionality. MARS is not
supported in ADO.NET 1.0 nor ADO.NET 1.1
Attach a database file on connect to a local SQL Server
Express instance:
"Server=.\SQLExpress;
AttachDbFilename=c:\asd\qwe\mydbfile.mdf;
Database=dbname;
Trusted_Connection=Yes;"
OR
"Server=.\SQLExpress;
AttachDbFilename=|DataDirectory|mydbfile.mdf;
Database=dbname;
Trusted_Connection=Yes;"
(Note: use |DataDirectory| when your database file resides
in the data directory)
Using "User Instance" on a local SQL Server Express
instance:
"Data Source=.\SQLExpress;
integrated security=true;
attachdbfilename=|DataDirectory|\mydb.mdf;user instance=true;"
Note: The "User Instance" functionality creates a new SQL
Server instance on the fly during connect. This works
only on a local SQL
Server 2005 instance and only when connecting using windows
authentication over local named pipes. The purpose is to
be able to create a full rights SQL Server instance to
a user with limited administrative rights on the computer.
To enable the functionality: sp_configure
'user instances enabled','1' (0 to disable)
Using SQL Server 2005 Express? Don't miss the server name
syntax: SERVERNAME\SQLEXPRESS (Substitute "SERVERNAME" with the name of the computer)
1) Whats the difference between Classic ASP and ASP.NET?
Major difference: Classic ASP is Interpreted. ASP.NET is Compiled. If code is changed, ASP.NET recompiles, otherwise does'nt.
Other differences: ASP works with VB as the language. ASP.NET works with VB.NET & C# as the languages (Also supported by other languages that run on the .NET Framework).
ASP.NET is the web technology that comes with the Microsoft .NET Framework. The main process in ASP.NET is called aspnet_wp.exe that accesses system resources. ASP.NET was launched in 2002 with version 1.0. Subsequent versions are 1.1 and version 2.0. ASP.NET is built up using thousands of objects, ordered in the System namespace. When an ASP.NET class is compiled, its called an assembly.
In Classic ASP, complex functionalities are achieved using COM components, that are nothing but component objects created using VB 6, C++ etc, and are usually in a DLL format. These components provide an exposed interface to methods in them, to the objects that reference these components. Last version of classic ASP is version 3.0. ASP has 7 main objects - Application, ASPError, ObjectContext, Request, Response, Server, Session.
2) What is the difference between
The old
ADO.NET breaks the functionality of the
3) Whats the difference betweeen Structure, Class and Enumeration
Structures and Enumerations are Value-Types. This means, the data that they contain is stored as a stack on the memory. Classes are Reference-Types, means they are stored as a heap on the memory.
Structures are implicitly derived from a class called System.ValueType. The purpose of System.ValueType is to override the virtual methods defined by System.Object. So when the runtime encounters a type derived from System.ValueType, then stack allocation is achieved. When we allocate a structure type, we may also use the new keyword. We may even make a constructor of a structure, but, remember, A No-argument constructor for a structure is not possible. The structure's constructor should always have a parameter.
So if we define the following structure
struct MyStruct
{
public int y,z;
}
and we create a structure type
MyStruct st = new MyStruct();
In case of a class, no-argument constructors are possible. Class is defined using the class keyword.
A struct cannot have an instance field, whereas a class can.
class A
{
int x = 5; //No error
...
}
struct
{
int x = 5; //Syntax Error
}
A class can inherit from one class (Multiple inheritance not possible). A Structure cannot inherit from a structure.
Enum is the keyword used to define an enumeration. An enumeration is a distinct type consisting of a set of named constants called the enumerator list. Every enumeration has an underlying type. The default type is "int". Note: char cant be the underlying data type for enum. First value in enum has value 0, each consequent item is increased by 1.
enum colors {red, green, blue, yellow};
Here, red is 0, green is 1, blue is 2 and so on.
An explicit casting is required to convert an enum value to its underlying type
int x = (int)colors.yellow;
4) What is the difference between abstract class and interface?
If a class is to serve the purpose of providing common fields and members to all subclasses, we create an Abstract class. For creating an abstract class, we make use of the abstract keyword. Such a class cannot be instantiated. Syntax below:
abstract public class Vehicle { }
Above, an abstract class named Vehicle has been defined. We may use the fields, properties and member functions defined within this abstract class to create child classes like Car, Truck, Bike etc. that inherit the features defined within the abstract class. To prevent directly creating an instance of the class Vehicle, we make use of the abstract keyword. To use the definitions defined in the abstract class, the child class inherits from the abstract class, and then instances of the Child class may be easily created.
Further, we may define abstract methods within an abstract class (analogous to C++ pure virtual functions) when we wish to define a method that does not have any default implementation. Its then in the hands of the descendant class to provide the details of the method. There may be any number of abstract methods in an abstract class. We define an abstract method using the abstract keyword. If we do not use the abstract keyword, and use the virtual keyword instead, we may provide an implementation of the method that can be used by the child class, but this is not an abstract method.
Remember, abstract class can have an abstract method, that does not have any implementation, for which we use the abstract keyword, OR the abstract class may have a virtual method, that can have an implementation, and can be overriden in the child class as well, using the override keyword. Read example below
Example: Abstract Class with Abstract method
namespace Automobiles
{
public abstract class Vehicle
{
public abstract void Speed() //No Implementation here, only definition
}
}
Example: Abstract Class with Virtual method
namespace Automobiles
{
public abstract class Vehicle
{
public virtual void Speed() //Can have an implementation, that may be overriden in child class
{
...
}
}
Public class Car : Vehicle
{
Public override void Speed()
//Here, we override whatever implementation is there in the abstract class
{
... //Child class implementation of the method Speed()
}
}
}
An Interface is a collection of semantically related abstract members. An interface expresses through the members it defines, the behaviors that a class needs to support. An interface is defined using the keyword interface. The members defined in an interface contain only definition, no implementation. The members of an interface are all public by default, any other access specifier cannot be used. See code below:
Public interface IVehicle //As a convention, an interface is prefixed by letter I
{
Boolean HasFourWheels()
}
Time to discuss the Difference between Abstract Class and Interface
1) A class may inherit only one abstract class, but may implement multiple number of Interfaces. Say a class named Car needs to inherit some basic features of a vehicle, it may inherit from an Aabstract class named Vehicle. A car may be of any kind, it may be a vintage car, a sedan, a coupe, or a racing car. For these kind of requirements, say a car needs to have only two seats (means it is a coupe), then the class Car needs to implement a member field from an interface, that we make, say ICoupe.
2) Members of an abstract class may have any access modifier, but members of an interface are public by default, and cant have any other access modifier.
3) Abstract class methods may OR may not have an implementation, while methods in an Interface only have a definition, no implementation.
5) Explain the access specifiers Public, Private, Protected, Friend, Internal, Default
The main purpose of using access specifiers is to provide security to the applications. The availability (scope) of the member objects of a class may be controlled using access specifiers.
1. PUBLIC
As the name specifies, it can be accessed from anywhere. If a member of a class is defined as public then it can be accessed anywhere in the class as well as outside the class. This means that objects can access and modify public fields, properties, methods.
2. PRIVATE
As the name suggests, it can't be accessed outside the class. Its the private property of the class and can be accessed only by the members of the class.
3. FRIEND/INTERNAL
Friend & Internal mean the same. Friend is used in VB.NET. Internal is used in C#. Friends can be accessed by all classes within an assembly but not from outside the assembly.
4. PROTECTED
Protected variables can be used within the class as well as the classes that inherites this class.
5. PROTECTED FRIEND/PROTECTED INTERNAL
The Protected Friend can be accessed by Members of the Assembly or the inheriting class, and ofcourse, within the class itself.
6. DEFAULT
A Default property is a single property of a class that can be set as the default. This allows developers that use your class to work more easily with your default property because they do not need to make a direct reference to the property. Default properties cannot be initialized as Shared/Static or Private and all must be accepted at least on argument or parameter. Default properties do not promote good code readability, so use this option sparingly.
6) What is the difference between Overriding and Shadowing?
Both Overriding and Shadowing are ways to alter the behaviour of members of a base class. Shadowing is a VB.NET concept. In C#, this concept is called Hiding, though there is a difference between the two.
When we do shadowing, we provide a new implementation to the base class member without overriding it. We may shadow a base class member in a derived class, by using the keyword shadows. The access level, return type, and the signature (means the datatypes of the arguments passed & the order of the types) of the derived class members which are shadowed, may differ from the base class.
In C#, we may achieve shadowing using the keyword new. However, when Hiding in C#, the access level, the signature, return type of the derived class must be same as the base class.
Overriding is the concept of providing a new implementation of derived class member as compared to its based class. In VB.NET, we do overriding using the overrides keyword, while in C#, overriding is achieved using the override keyword. For a class member to be overridable, we use the keyword virtual while defining it (in C#), and we use the keyword overridable (in VB.NET), though if we leave out specifying the overridable keyword, the member is overridable by default.
7) What is the difference between a DLL and an EXE?
In .NET, an assembly may become a DLL or an EXE. Yet, there is a major underlying difference between the two.
An EXE is an executable file, that may run on its own. Its independant. Where as a DLL is a Dynamic Link Library, that binds to an exe, or another DLL at runtime.
A DLL has an exposed interface, through which members of the assembly may be accessed by those objects that require it.
A DLL runs in tandem with the application space in memory, as the application references it. Whereas an EXE is independant, and runs as an independant process.
8) Whats the difference between a class and an object?
In any object Oriented language, an object is the backbone of everything that we see. A class is a blueprint that describes how an instance of it (object) will behave. To create a class, we define it in a "Code File", with an extension *.cs or *.vb. We make use of the keyword class.
Example
Lets create a class named Laptop
public class Laptop
{
private string sbrand;
public Laptop() {}
public Laptop(string name)
{
sbrand = name;
}
}
From our code that references this class, we write...
Laptop lp = new Laptop("Lenovo"); //Passing a variable to the class constructor
Once the class object is created, the object may be used to invoke the member functions defined within the class. We may allocate any number of objects using the new keyword. The new keyword returns a reference to an object on the heap. This reference is not to the actual object itself. The variable being refered is stored on a stack for usage in the application. When we allocate an object to a heap, its managed by the .NET runtime. The garbage collector takes care of the object by removing it from the heap, when it is no longer reachable by any part of the code.
9) What is the difference between Shared and Static?
They both mean the same. Shared is used in VB.NET. Static is used in C#.
When the static keyword is used to declare a class, the member in context must be directly invoked from the class, rather than from the instance. Consider the following example
//Consider writing the following line of code...
Console obj = new Console();
obj.Writeline("Vishal likes static members"); //This line does'nt print
//This does'nt work, because WriteLine is a static method defined in the class Console
//The Console class is a static class
To use static members, give a reference to the exact class, as an instance in this case won't work.
To make this work, write...
Console.Writeline("Vishal likes static members");
To work with members of static classes, no need to create their instances.
Static Member - A class member declared with the keyword static is a static member. A static member is owned by the class, not by its instances (objects of the class).
Note that static members are actually class members, while non-static members are instance members (means they are owned by the instances). Both in C# & VB.NET, we may create static/shared events, properties, fields and functions.
Note Indexers in C# cannot be declared static.
Note Static member functions cannot access non-static members directly.
10) What is the difference between value type and reference type? Can a value type contain NULL values?
In simple words, all value based types are allocated on the stack, while all reference based types are allocated on the heap. What does this mean? A value type contains the actual value. A reference type contains a reference to the value. When a value type is assigned to another value type, it is copied. When a reference type is assigned to another reference type, a reference is assigned to the value.
By saying stack, we mean things are kept one on top of the other. We keep track of each value at the top. By saying heap, we mean things are kept in a mashed order. We keep track of each value by its address, that is referenced by a pointer to it.
All value types are implicitly derived from System.ValueType. This class actually overrides the implementation in System.Object, the base class for all objects which is a reference type itself.
Data types like integers, floating point numbers, character data, Boolean values, Enumerations and Structures are examples of Value Types. Classes, Strings, Arrays are examples of Reference Types.
A value type may not contain NULL values. Reference types may contain NULL values.
It is not possible to derive new types from Value Types. This is possible in Reference types. However, Value Types like Structures can implement interfaces.
11) Whats the difference between MSIL and CIL?
MSIL is the name given to the intermediate language in .NET Framework Beta, 1.0 and 1.1. From version 2.0 onwards, the intermediate language is called CIL. We can say, MSIL is the old name. MSIL stands for Microsoft Intermediate Language. CIL stands for Common Intermediate Language. Its actually a low level human readable language implementation of CLI.
There is not much difference between the two. Compilers like vbc.exe and csc.exe compile the code into intermediate language. CIL is the name submitted by Microsoft to the European Computer Manufacturer's Association(ECMA) as a standard.
12) What is the difference between a Class Library and a Namespace?
Class Library is another major entity of the .NET Framework (the other being the CLR). This library gives the program access to runtime environment. The class library consists of lots of prewritten code that all the applications created in .NET will use. The code for all the elements like forms, controls actually comes from the class library. The main class library in .NET is mscorlib.dll. This library contains a large number of core types that encapsulate a wide variety of common tasks. When a .NET application, there is automatic access to this library. We may view the class libraries provided by the .NET Framework by seeing the Global Assembly Cache (Go to C:\Windows\Assembly OR C:\Winnt\Assembly).
Namespace is a grouping of related types contained in an assembly. For example, the System.Drawing namespace consists of classes, methods that are grouped together to achieve similar tasks.
Note that a single assembly like mscorlib.dll may contain any number of namespaces. In fact, namespaces may be nested (means a namespace within a namespace) to arrange classes in a hierarchical fashion.
Also note that any language, that works on the .NET environment, targets the same set of namespaces & types provided by the .NET framework.
13) What is the difference between String and StringBuilder?
Both String and StringBuilder are classes used to handle strings.
The most common operation with a string is concatenation. This activity has to be performed very efficiently. When we use the "String" object to concatenate two strings, the first string is combined to the other string by creating a new copy in the memory as a string object, and then the old string is deleted. This process is a little long. Hence we say "Strings are immutable".
When we make use of the "StringBuilder" object, the Append method is used. This means, an insertion is done on the existing string. Operation on StringBuilder object is faster than String operations, as the copy is done to the same location. Usage of StringBuilder is more efficient in case large amounts of string manipulations have to be performed.
14) What is the difference between Web Services and Remoting?
Both Remoting and Web Services are ways of communication between applications.
Remoting - In remoting, the applications involved in the communication process may be located on the same computer, different computers in a same or different network. In remoting, both applications know about each other. A proxy of an application object is created on the other application.
Web Services - Communication between applications using web services is platform independent and programming independent. The application that consumes the web service, simply accesses it, without needing to know how this web service has actually been implemented & created.
Here are some of the major differences:
* ASP.NET Web Services may be accessed using HTTP only. Remoting objects may be accessed over any protocol like TCP, SMTP, HTTP
* Web Service are Stateless, whereas Remoting has support for both stateless and with-state environment, which is achieved using Singleton and Singlecall activation
* ASP.NET provides good support to create Web Services. They are easy to deploy. In comparison, Remoting is little complex.
* Web services may be considered very reliable, due to the fact that they are hosted on IIS. In remoting, if IIS is'nt used, then methods like plumbing have to be used to ensure the application reliability.
* In .NET, when we create an application that consumes a web service, the web service may or may not be built using .NET. But while implementing Remoting in .NET, both the applications must be built in .NET.
* Using web services, only a limited number of types may be serialized (XML). Using Remoting, objects like SOAP objects, Binary objects & XML Objects may be serialized.
15) What is the difference between a Public Assembly and a Private Assembly?
An assembly is the basic building block in .NET. It is the compiled format of a class, that contains Metadata, Manisfest & Intermediate Language code.
An assembly may be either Public or Private. A public assembly means the same as Shared Assembly.
Private Assembly - This type of assembly is used by a single application. It is stored in the application's directory or the applications sub-directory. There is no version constraint in a private assembly.
Shared Assembly or Public Assembly - A shared assembly has version constraint. It is stored in the Global Assembly Cache (GAC). GAC is a repository of shared assemblies maintained by the .NET runtime. It is located at C:\Windows\Assembly OR C:\Winnt\Assembly. The shared assemblies may be used by many applications. To make an assembly a shared assembly, it has to be strongly named. In order to share an assembly with many applications, it must have a strong name.
A Strong Name assembly is an assembly that has its own identity, through its version and uniqueness.
In order to convert a private assembly to a shared assembly, i.e. to create a strongly named assembly, follow the steps below...
1) Create a strong key using the sn.exe tool. This is used to created a cryptographic key pair. The key pair that is generated by the Strong Name tool can be kept in a file or we can store it our your local machine's Crytographic Service Provider (CSP). For this, goto the .NET command interpreter, and type the following...
sn -k C:\samplekey.snk
This will create a strong key and save it to the location C:\samplekey.snk 2) If the key is stored in a file, just like we have done above, we use the attribute AssemblyKeyFileAttribute. This belongs to the namespace System.Reflection.AssemblyKeyFileAttribute. If the key was in the CSP, we would make use of System.Reflection.AssemblyKeyNameAttribute.
Go to the assemblyinfo.vb file of your project. Open this file. Make the following changes in this file...
We may write this in our code as well, like this...
Imports System.Reflection
Namespace StrongName
Public class Sample
End Class
End Namespace
3) Build your project. Your assembly is now strongly named.
Installing the Shared assembly in GAC...
Go to .NET command interpreter, use the tool gacutil.exe
Type the following...
gacutil /i sampleclass.dll
To uninstall it, use... gacutil /u sampleclass.dll. Visual Studio.NET provides a GUI tool for viewing all shared assemblies in the GAC.
16) What is the difference between Trace and Debug?
Trace and Debug - There are two main classes that deal with tracing - Debug and Trace. They both work in a similar way - the difference is that tracing from the Debug class only works in builds that have the DEBUG symbol defined, whereas tracing from the Trace class only works in builds that have the TRACE symbol defined. Typically this means that you should use System.Diagnostics.Trace.WriteLine for tracing that you want to work in debug and release builds, and System.Diagnostics.Debug.WriteLine for tracing that you want to work only in debug builds.
Tracing is actually the process of collecting information about the program's execution. Debugging is the process of finding & fixing errors in our program. Tracing is the ability of an application to generate information about its own execution. The idea is that subsequent analysis of this information may help us understand why a part of the application is not behaving as it should and allow identification of the source of the error.
We shall look at two different ways of implementing tracing in .NET via the System.Web.TraceContext class via the System.Diagnostics.Trace and System.Diagnostics.Debug classes. Tracing can be thought of as a better alternative to the response.writes we used to put in our classic ASP3.0 code to help debug pages.
If we set the Tracing attribute of the Page Directive to True, then Tracing is enabled. The output is appended in the web form output. Messeges can be displayed in the Trace output using Trace.Warn & Trace.Write.
NOTE The only difference between Trace.Warn & Trace.Write is that the former has output in red color. If the trace is false, there is another way to enable tracing. This is done through the application level. We can use the web.config file and set the trace attribute to true. Here we can set
Note that the Page Directive Trace attribute has precedence over th application level trace attribute of web.config. While using application level tracing, we can view the trace output in the trace.axd file of the project.
17) What is the difference between Server.Transfer and Response.Redirect?
Both "Server" and "Response" are objects of ASP.NET. Server.Transfer and Response.Redirect both are used to transfer a user from one page to another. But there is an underlying difference.
//Usage of Server.Transfer & Response.Redirect
Server.Transfer("Page2.aspx");
Response.Redirect("Page2.aspx");
The Response.Redirect statement sends a command back to the browser to request the next page from the server. This extra round-trip is often inefficient and unnecessary, but this established standard works very well. By the time Page2 is requested, Page1 has been flushed from the server’s memory and no information can be retrieved about it unless the developer explicitly saved the information using some technique like session, cookie, application, cache etc.
The more efficient Server.Transfer method simply renders the next page to the browser without an extra round trip. Variables can stay in scope and Page2 can read properties directly from Page1 because it’s still in memory. This technique would be ideal if it wasn’t for the fact that the browser is never notified that the page has changed. Therefore, the address bar in the browser will still show “Page1.aspx” even though the Server.Transfer statement actually caused Page2.aspx to be rendered instead. This may occasionally be a good thing from a security perspective, it often causes problems related to the browser being out of touch with the server. Say, the user reloads the page, the browser will request Page1.aspx instead of the true page (Page2.aspx) that they were viewing. In most cases, Response.Redirect and Server.Transfer can be used interchangeably. But in some cases, efficiency or usability may be the deciding factor in choosing.
18) What is the difference between Server.Transfer and Server.Execute?
Both Server.Transfer and Server.Execute were introduced in Classic ASP 3.0 (and still work in ASP.NET).
When Server.Execute is used, a URL is passed to it as a parameter, and the control moves to this new page. Execution of code happens on the new page. Once code execution gets over, the control returns to the initial page, just after where it was called. However, in the case of Server.Transfer, it works very much the same, the difference being the execution stops at the new page itself (means the control is'nt returned to the calling page).
In both the cases, the URL in the browser remains the first page url (does'nt refresh to the new page URL) as the browser is'nt requested to do so.
19) What is the difference between Authorization and Authentication?
Both Authentication and Authorization are concepts of providing permission to users to maintain different levels of security, as per the application requirement.
Authentication is the mechanism whereby systems may securely identify their users. Authentication systems depend on some unique bit of information known only to the individual being authenticated and the authentication system.
Authorization is the mechanism by which a system determines what level of access a particular authenticated user should have to secured resources controlled by the system.
When a user logs on to an application/system, the user is first Authenticated, and then Authorized.
ASP.NET has 3 ways to Authenticate a user:
1) Forms Authentication
2) Windows Authentication
3) Passport Authentication (This is obsolete in .NET 2.0)
The 4th way is "None" (means no authentication)
The Authentication Provider performs the task of verifying the credentials of the user ans decides whether a user is authenticated or not. The authentication may be set using the web.config file.
Windows Authentication provider is the default authentication provider for ASP.NET applications. When a user using this authentication logs in to an application, the credentials are matched with the Windows domain through IIS.
There are 4 types of Windows Authentication methods:
1) Anonymous Authentication - IIS allows any user
2) Basic Authentication - A windows username and password has to be sent across the network (in plain text format, hence not very secure). 3) Digest Authentication - Same as Basic Authentication, but the credentials are encrypted. Works only on IE 5 or above
4) Integrated Windows Authentication - Relies on Kerberos technology, with strong credential encryption
Forms Authentication - This authentication relies on code written by a developer, where credentials are matched against a database. Credentials are entered on web forms, and are matched with the database table that contains the user information.
Authorization in .NET - There are two types:
FileAuthorization - this depends on the NTFS system for granting permission
UrlAuthorization - Authorization rules may be explicitly specified in web.config for different web URLs.
20) What is the difference between ExecuteScalar and ExecuteNonQuery? What is ExecuteReader?
ExecuteScalar - Returns only one value after execution of the query. It returns the first field in the first row. This is very light-weight and is perfect when all your query asks for is one item. This would be excellent for receiving a count of records (Select Count(*)) in an sql statement, or for any query where only one specific field in one column is required.
ExecuteNonQuery - This method returns no data at all. It is used majorly with Inserts and Updates of tables. It is used for execution of DML commands.
Example:
SqlCommand cmd = new SqlCommand("Insert Into t_SomeTable Values('1','2')",con);
//note that con is the connection object
con.Open();
cmd.ExecuteNonQuery(); //The SQL Insert Statement gets executed
ExecuteReader - This method returns a DataReader which is filled with the data that is retrieved using the command object. This is known as a forward-only retrieval of records. It uses our SQL statement to read through the table from the first to the last record.
21) What is the difference between a DataReader and Dataset in ADO.NET?
A DataReader works in a connected environment, whereas DataSet works in a disconnected environment.
A DataReader object represents a forward only, read only access to data from a source. It implements IDataReader & IDataRecord interfaces. For example, The SQLDataReader class can read rows from tables in a SQL Server data source. It is returned by the ExecuteReader method of the SQLCommand class, typically as a result of a SQL Select statement. The DataReader class' HasRows property can be called to determine whether the DataReader retrieved any rows from the source. This can be used before using the Read method to check whether any data has been retrieved.
Example
Dim objCmd as New SqlCommand("Select * from t_Employees", objCon)
objCon.Open()
Dim objReader as SqlDataReader
objReader = objCom.ExecuteReader(CommandBehavior.CloseConnection)
If objReader.HasRows = True then
Do While objReader.Read()
ListBox1.Items.Add(objReader.GetString(0) & vbTab & objReader.GetInt16(1))
Loop
End If
objReader.Close()
(NOTE: XmlReader object is used for Forward only Read only access of XML).
A DataSet represents an in-memory cache of data consisting of any number of inter-related DataTable objects. A DataTable object represents a tabular block of in-memory data. Further, a DataRow represents a single row of a DataTable object. A Dataset is like a mini-database engine, but its data is stored in the memory. To query the data in a DataSet, we can use a DataView object.
Example
Dim objCon as SqlConnection = New SqlConnection("server=(local);database=NameOfYourDb;user id=sa; password=;)
Dim da as New SqlDataAdapter
Dim ds as DataSet = New DataSet
da.SelectCommand.Connection = objCon 'The Data Adapter manages on its own, opening & closing of connection object
da.SelectCommand.CommandText = "Select * from t_SomeTable"
da.Fill(ds,"YourTableName")
Suppose you want to bind the data in this dataset to a gridview
Gridview1.DataSource = ds
Gridview1.DataMember = "YourTableName"
Gridview1.Databind()
22) What is the difference between System.Array.CopyTo and System.Array.Clone in .NET?
The Clone() method returns a new array (a shallow copy) object containing all the elements in the original array. The CopyTo() method copies the elements into another existing array. Both perform a shallow copy.
23) What is the difference between a Thread and Process?
A process is a collection of virtual memory space, code, data, and system resources. A thread is code that is to be serially executed within a process. A processor executes threads, not processes, so each application has at least one process, and a process always has at least one thread of execution, known as the primary thread. A process can have multiple threads in addition to the primary thread. Prior to the introduction of multiple threads of execution, applications were all designed to run on a single thread of execution.
When a thread begins to execute, it continues until it is killed or until it is interrupted by a thread with higher priority (by a user action or the kernel’s thread scheduler). Each thread can run separate sections of code, or multiple threads can execute the same section of code. Threads executing the same block of code maintain separate stacks. Each thread in a process shares that process’s global variables and resources.
Tuesday, November 4, 2008
1) What do you mean by Share Point Portal?
Here I have taken information regarding Share Point Portal Server 2003 provides mainly access to the crucial business information and applications. With the help of Share Point Server we can server information between Public Folders, Data Bases, File Servers and the websites that are based on Windows server 2003. This Share Point Portal is integrated with MSAccess and Windows servers, so we can get a Wide range of document management functionality. We can also create a full featured portal with readymade navigation and structure.
2) What is cross page posting in ASP.NET2.0?
When we have to post data from one page to another in application we used server. Transfer method but in this the URL remains the same but in cross page posting there is little different there is normal post back is done but in target page we can access values of server control in the source page. This is quite simple we have to only set the PostBackUrl property of Button,LinkButton or imagebutton which specifies the target page.In target page we can access the PreviousPage property. And we have to use the @PreviousPageType directive.We can access control of PreviousPage by using the findcontrol method. When we set the PostBackURL property ASP.NET framework bind the HTML and JavaScript function automatically.
3) How to call method that handles the Click event for several buttons?
Protected Sub AnyClicked(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click, Button2.Click, Button3.Click
Dim b As Button = CType(sender, Button)
Response. Write("You clicked the button labeled " & b.ID) End Sub
4) What do you mean by Web Part Control in asp.net?
ASP.NET Web Parts controls are the integrated controls which helps in creation of Web sites that also help users to modify the content as well as appearance, and behavior of pages of web sites that are open in browser.
5) What changes are done in IIS 6.0 over IIS 5.0?
IIS makes easy to get information. ISS 6.0 is the next latest of web server available in Windows Server 2003 platform. IIS 6.0 contains several enhancements over IIS 5.0 that are mainly to increase reliability, manageability, scalability, and security. IIS 6.0 is a key component of the Windows Server 2003 application platform, using which you can develop and deploy high performance ASP.NET Web applications, and XML Web Services.
6) Com Marshler function in .NET?
Com Marshler is useful component of CLR.Main work of marshal data between Managed and Unmanaged environment .It helps in representation of data across different execution environment. Its also convert data format between manage and unmanaged code. By the helps of Com Marshlar CLR allows manage code to interoperate with unmanaged code.
7) How Visual SourceSafe helps us?
One of the powerful tool provided by Microsoft to keep up-to-date of files system its keeps records of file history once we add files to source safe it can be add to database and the changes ade by different user to this files are maintained in database from that we can get the older version of files to. This also helps in sharing, merging of files.
8) What is main difference between GridLayout and FormLayout ?
GridLayout helps in providing absolute positioning of every control placed on the page. It is easier to develop page with absolute positioning because control can be placed any where according to our requirement. But FormLayout is little different only experience Web Developer used this one reason is it is helpful for wider range browser. If there is absolute positioning we can notice that there are number of DIV tags. But in FormLayout whole work are done through the tables.
9) What is the purpose of IIS?
We can call IIS(Internet Information Services) a powerful Web server that helps us creating highly reliable, scalable and manageable infrastructure for Web application which runs on Windows Server 2003. IIS helps development center and increase Web site and application availability while lowering system administration costs. It also runs on Windows NT/2000 platforms and also for above versions. With IIS, Microsoft includes a set of programs for building and administering Web sites, a search engine, and support for writing Web-based applications that access database. IIS also called http server since it process the http request and gets http response.
10) How to start Outlook,NotePad file in AsP.NET with code ?
Here is the syntax to open outlook or notepad file in ASP.NET VB.NET Process.Start("Notepad.exe") Process.Start("msimn.exe"); C#.NET System.Diagnostics.Process.Start("msimn.exe"); System.Diagnostics.Process.Start("Notepad.exe");
11) What you thing about the WebPortal ?
Web portal is nothing but a page that allows a user to customize his/her homepage. We can use Widgets to create that portal we have only to drag and drop widgets on the page. The user can set his Widgets on any where on the page where he has to get them. Widgets are nothing but a page area that helps particular function to response. Widgets example are address books, contact lists, RSS feeds, clocks, calendars, play lists, stock tickers, weather reports, traffic reports, dictionaries, games and another such beautiful things that we can not imagine. We can also say Web Parts in Share Point Portal. These are one of Ajax-Powered.
12) Can you define what is SharePoint and some overview about this?
SharePoint helps workers for creating powerful personalized interfaces only by dragging and drop pre-defined Web Part Components. And these Web Parts components also help non programmers to get information which care and customize the appearance of Web pages. To under stand it we take an example one Web Part might display a user's information another might create a graph showing current employee status and a third might show a list of Employees Salary. This is also possible that each function has a link to a video or audio presentation. So now Developers are unable to create these Web Part components and make them available to SharePoint users.
13) What is different between WebUserControl and in WebCustomControl?
Web user controls :- Web User Control is Easier to create and another thing is that its support is limited for users who use a visual design tool one good thing is that its contains static layout one more thing a separate copy is required for each application.
Web custom controls:-Web Custom Control is typical to create and good for dynamic layout and another thing is it have full tool support for user and a single copy of control is required because it is placed in Global Assembly cache.
14) What is Sandbox in SQL server and explain permission level in Sql Server?
Sandbox is place where we run trusted program or script which is created from the third party. There are three type of Sandbox where user code runs.
Safe Access Sandbox:-Here we can only create stored procedure, triggers, functions, datatypes etc.But we does not have access memory, disk etc.
External Access Sandbox:-We can access File systems outside the box. We can not play with threading, memory allocation etc.
Unsafe Access Sandbox:-Here we can write unreliable and unsafe code.
15) How many types of cookies are there in .NET?
Two type of cookies.
a) single valued eg request.cookies(”UserName”).value=”dotnetquestion”
b)Multivalued cookies. These are used in the way collections are used example
request.cookies(”CookiName”)(”UserName”)=”dotnetquestionMahesh”
request.cookies(”CookiName”)(”UserID”)=”interview″
16) When we get Error 'HTTP 502 Proxy Error' ?
We get this error when we execute ASP.NET Web pages in Visual Web Developer Web server, because the URL randomly select port number and proxy servers did not recognize the URL and return this error. To resolve this problem we have to change settings in Internet Explorer to bypass the proxy server for local addresses, so that the request is not sent to the proxy.
17) What do you mean by three-tier architecture?
The three-tier architecture was comes into existence to improve management of code and contents and to improve the performance of the web based applications. There are mainly three layers in three-tier architecture. the are define as follows
(1)Presentation
(2)Business Logic
(3)Database
(1)First layer Presentation contains mainly the interface code, and this is shown to user. This code could contain any technology that can be used on the client side like HTML, JavaScript or VBScript etc.
(2)Second layer is Business Logic which contains all the code of the server-side .This layer have code to interact with database and to query, manipulate, pass data to user interface and handle any input from the UI as well.
(3)Third layer Data represents the data store like MS Access, SQL Server, an XML file, an Excel file or even a text file containing data also some additional database are also added to that layers.
18) What is Finalizer in .NET define Dispose and Finalize?
We can say that Finalizer is the method that's helps in cleanup the code that is executed before object is garbage collected .The process is called finalization. There are two methods of finalizer Dispose and Finalize .There is little different between two of this method.
When we call Dispose method is release all the resources hold by an object as well as all the resources hold by the parent object. When we call Dispose method it clean managed as well as unmanaged resources.
Finalize method also cleans resources but finalize call dispose clears only the unmanaged resources because in finalization the garbage collector clears all the object hold by managed code so finalization fails to prevent those one of method is used that is: GC.SuppressFinalize.
19) Define SMTPclient class in DotNet framework class library?
Each class in dotnet framework includes some properties, method and events. These properties ,methods and events are member of a class.SMTPclient class mainly concern with sending mail. These classes contain the folling member.
Properties:-
Host:-The name or IP address of email server.
Port:-Port that is use when sending mail.
Methods:-
Send:-Enables us to send email synchronously.
SendAsynchronous:-Enables us to send an email asynchronously.
Event:-
SendCompleted:-This event raised when an asynchronous send operation completes.
20) What is late binding?
When code interacts with an object dynamically at runtime .because our code literally doesn’t care what type of object it is interacting and with the methods that’s are supported by object and with the methods thats are supported by object .The type of object is not known by the IDE or compiler, no Intellisense nor compile-time syntax checking is possible but we get unprecedented flexibility in exchange. If we enable strict type checking by using option strict on at the top of our code modules, then IDE and compiler will enforce early binding behavior .By default late binding is done.
21) Does .NET CLR and SQL SERVER run in different process?
Dot Net CLR and all .net relates application and Sql Server run in same process or we can say that that on the same address because there is no issue of speed because if these two process are run in different process then there may be a speed issue created one process goes fast and other slow may create the problem.
22) What is Com Marshler and its importance in .NET?
Com Marshler is one of useful component of CLR. Its Task is to marshal data between Managed and Unmanaged environment .It helps in representation of data across different execution enviroment.It performs the conversion of data format between manage and unmanaged code. By the helps of Com Marshlar CLR allows manage code to interoperate with unmanaged code.
23) What is CSU and its description?
CSU stands for comma separate values also called comma delimited. It is plain text file which stores spreadsheets or basic data type in very simple format. One record in each line and each field separated with comma's it is often used to transfer large amount spreadsheet data or database information between programs.
24) The IHttpHandler and IHttpHandlerFactory interfaces?
The IHttpHandler interface is implemented by all the handlers. The interface consists of one property called IsReusable. The IsReusable property gets a value indicating whether another request can use the IHttpHandler instance. The method ProcessRequest() allows you to process the current request. This is the core place where all your code goes. This method receives a parameter of type HttpContext using which you can access the intrinsic objects such as Request and Response. The IHttpHandlerFactory interface consists of two methods - GetHandler and ReleaseHandler. The GetHandler() method instantiates the required HTTP handler based on some condition and returns it back to ASP.NET. The ReleaseHandler() method allows the factory to reuse an existing handler.
25) What is Viewstate?
View state is used by the ASP.NET page framework to automatically save the values of the page and of each control just prior to rendering to the page. When the page is posted, one of the first tasks performed by page processing is to restore view state.
State management is the process by which you maintain state and page information over multiple requests for the same or different pages.
Client-side options are:
| * The ViewState property | * Query strings |
| * Hidden fields | * Cookies |
Server-side options are:
| * Application state | * Session state | * DataBase |
Use the
ASP.NET provides the following ways to retain variables between requests:
Context.Handler object Use this object to retrieve public members of one Web form’s class from a subsequently displayed Web form.
Query strings Use these strings to pass information between requests and responses as part of the Web address. Query strings are visible to the user, so they should not contain secure information such as passwords.
Cookies Use cookies to store small amounts of information on a client. Clients might refuse cookies, so your code has to anticipate that possibility.
View state ASP.NET stores items added to a page’s ViewState property as hidden fields on the page.
Session state Use Session state variables to store items that you want keep local to the current session (single user).
Application state Use Application state variables to store items that you want be available to all users of the application.
26) DOTNET PAGE LIFECYCLE?
While excuting the page, it will go under the fallowing steps(or fires the events) which collectivly known as Page Life cycle.
Page_Init -- Page Initialization
LoadViewState -- View State Loading
LoadPostData -- Postback data processing
Page_Load -- Page Loading
RaisePostDataChangedEvent -- PostBack Change Notification
RaisePostBackEvent -- PostBack Event Handling
Page_PreRender -- Page Pre Rendering Phase
SaveViewState -- View State Saving
Page_Render -- Page Rendering
Page_UnLoad -- Page Unloading
27) What is Satellite Assemblies ?
Satellite assemblies are often used to deploy language-specific resources for an application. These language-specific assemblies work in side-by-side execution because the application has a separate product ID for each language and installs satellite assemblies in a language-specific subdirectory for each language. When uninstalling, the application removes only the satellite assemblies associated with a given language and .NET Framework version. No core .NET Framework files are removed unless the last language for that .NET Framework version is being removed. For example, English and Japanese editions of the .NET Framework version 1.1 share the same core files. The Japanese .NET Framework version 1.1 adds satellite assemblies with localized resources in a \ja subdirectory. An application that supports the .NET Framework version 1.1, regardless of its language, always uses the same core runtime files.
28) What is CAS?
CAS: CAS is the part of the .NET security model that determines whether or not a piece of code is allowed to run, and what resources it can use when it is running. For example, it is CAS that will prevent a .NET web applet from formatting your hard disk. How does CAS work? The CAS security policy revolves around two key concepts - code groups and permissions. Each .NET assembly is a member of a particular code group, and each code group is granted the permissions specified in a named permission set. For example, using the default security policy, a control downloaded from a web site belongs to the 'Zone - Internet' code group, which adheres to the permissions defined by the 'Internet' named permission set. (Naturally the 'Internet' named permission set represents a very restrictive range of permissions.)
29) Automatic Memory Management?
Automatic Memory Management: From a programmer's perspective, this is probably the single biggest benefit of the .NET Framework. No, I'm not kidding. Every project I've worked on in my long career of DOS and Windows development has suffered at some point from memory management issues. Proper memory management is hard. Even very good programmers have difficulty with it. It's entirely too easy for a small mistake to cause a program to chew up memory and crash, sometimes bringing the operating system to a screeching halt in the process.
Programmers understand that they're responsible for releasing any memory that they allocate, but they're not very good at actually doing it. In addition, functions that allocate memory as a side effect abound in the Windows API and in the C runtime library. It's nearly impossible for a programmer to know all of the rules. Even when the programmer follows the rules, a small memory leak in a support library can cause big problems if called enough.
The .NET Framework solves the memory management problems by implementing a garbage collector that can keep track of allocated memory references and release the memory when it is no longer referenced. A large part of what makes this possible is the blazing speed of today's processors. When you're running a 2 GHz machine, it's easy to spare a few cycles for memory management. Not that the garbage collector takes a huge number of cycles--it's incredibly efficient.
The garbage collector isn't perfect and it doesn't solve the problem of mis-managing other scarce resources (file handles, for example), but it relieves programmers from having to worry about a huge source of bugs that trips almost everybody up in other programming environments.
On balance, automatic memory management is a huge win in almost every situation.
30) What Language familiar to CLR?
Any language that can be compiled into Microsoft Intermediate Language (MSIL) is considered a .NET-compliant language. Following are a few of the popular .NET-compliant languages supported by CLR:
| APL | COBOL | Component Pascal | Eiffel |
| Fortran | Haskell | JScript | Mercury |
| Oberon | Pascal | Perl | Python |
| Smalltalk | Visual Basic | Visual C# | Visual C++ |