Friday, March 26, 2010

What is the difference between Server.Transfer and response.Redirect?

Select Answer:

• 1. No difference

• 2. Server.Transfer needs a Round Trip, Response.Rediect not

• 3. Response.Rediect needs Rountrip to bowser Server.Transfer does not need a Round Trip,

• 4. Server.Transfer can transfer user between two applications

Ans: 3

How many types of errors r there in ASP.NET? what r they?

Select Answer:

• 1. 4 types. Configuration,Runtime,compilation and parser errors

• 2. 2 types. Runtime and Compilation errors

• 3. 2 types. Configuration and Parser errrors

• 4. none of the above


What is the default authendication mode in
Three are three types of authendication mode available in . by default windows authendication.

Select Answer:

• 1. Windows

• 2. Passport

• 3. Form

Ans: 1

What happens if we remove session tag from web.cofig file ?

Select Answer:

• 1. sessions will not work

• 2. sessions will work

• 3. cookies will not be created

• 4. none


which class use to delete ,update ,select data in dataset.

Select Answer:

• 1. sqldataAdapter

• 2. sqlDataReader

• 3. SqlCommand

• 4. None


How to set focus in a textbox in after click on a button ?

Select Answer:

• 1. using Java script code textbox.focus and register it in by page.registerecript

• 2. can't focus by coding

• 3. use setfocus method

• 4. use keypress event with keycode property


if you develop a simple web page and use only text box than which one is better way for develop ?

Select Answer:

• 1. use only HTML Textbox control and for code make them runat server

• 2. use web form textbox

• 3. both


how to open more than one datareader at time ??

Select Answer:

• 1. use different Datareader varibles.

• 2. use different Datareader and connection variable and connection must be connected

• 3. use different datareader with signle connection and connection status must be connected

• 4. can't use more than one datatreader at a time


How to add 3rd party component ?

Select Answer:

• 1. By Add/Remove Items in PRoject Menu.

• 2. Add Reference of Dll file and palce their code where programmer want to use

• 3. can't add 3rd party component in

• 4. Require .OCX files of add component in


which component can be use for reporting in

Select Answer:

• 1. HTML Table.

• 2. data grid

• 3. Data Reapter

• 4. All of above


Advantage fo Disconneted mode in ?

Select Answer:

• 1. automatically dump data at client pc.

• 2. user data can be update and retrieve in dataset and when connection connted update values with serve

• 3. not neccessary to connect with server

• 4. all of above

Ans: 2

How to execute java script code in back-end code. ??

Select Answer:

• 1. Page.RegisterScript.

• 2. Page.Language='Java Script'

• 3. To set Defalut Langaue Java Script in Virtual Directory

• 4. back end automatic provide this facility


How to deploy a ASp.Net Web Application as Web Site on Web Server ?

Select Answer:

• 1. Run Web setup on Web Server.

• 2. Register application dll files on web server

• 3. install at locat pc and copy vitural directory on web server

• 4. Copy all project files on web server


Name the tool which converts from resx file to resources file which will be used in building satellite assemblies?

Select Answer:

• 1. SN.exe

• 2. AL.exe

• 3. Ngen.exe

• 4. Resgen.exe

• 5. None


What does WSDL stand for?

Select Answer:

• 1. Web System Description Language

• 2. Web Services Details Language

• 3. Web Services Design Language

• 4. Web Services Description Language


Which one of the following statements indicates ASP.NET’s advantage over ASP?

Select Answer:

• 1. Compiled Code

• 2. Caching

• 3. Web Controls

• 4. All of the above


What is Page Caching

Select Answer:

• 1. Keep the page with u

• 2. Keep a copy of the page anywhere

• 3. Delete the page

• 4. Carry the whole page in the session object

• 5. All of the above


Is there any significant difference between Link Button and Button in ASP.NET?

Select Answer:

• 1. Yes

• 2. No

• 3. Don't know


Can ASP and ASP.Net share session variables?

Select Answer:

• 1. yes

• 2. no

• 3. no, both support session variables but they cannot be shared


What id the default namespace for the web services?

Select Answer:

• 1. System.Web.WebServices

• 2. WebServices

• 3. Service1

• 4.

• 5. None


What is a satellite Assembly?

Select Answer:

• 1. A peripheral assembly designed to monitor permissions requests from an application?

• 2. Any DLL file used by an EXE file

• 3. An assembly containing localized resources for another assembly

• 4. An assembly designed to alter the appearance or ‘skin’ of an application

• 5. None of these


How can we fix that if any error will come in my live website, the error should not be displayed to site user. He will get an SORRY MESSAGE and a mail should be sent to Admin of website with following information.
1. Error Type
2. Description of Error
3. Line Number
4. Error source
5. Script Name

Select Answer:

• 1. Can put an Exception Handler

• 2. Can set some settings in IIS

• 3. Can set Some settings in Web.Config

• 4. It is not possible


Which one of the following objects is used to create a foreign key between two DataTables?

Select Answer:

• 1. DataRelation

• 2. DataRelationship

• 3. DataConstraint

• 4. DataKey

• 5. DataForeignKey


Which interface provides a fast, connected, forward-only access to a data source?

Select Answer:

• 1. IDataRecord

• 2. IDatabase

• 3. IDataCursor

• 4. IDataReader

• 5. IdataSet


Which is the best approach to move very large files from a web server to a browser client.

Select Answer:

• 1. Allow direct access to the file.

• 2. Using Response.WriteFile

• 3. Streaming the File using Response.BinaryWrite

• 4. Use an ISAPI Filter or improve by Upgrading to IIS 6.0 and running in Isolation mode

Can we manipulate Sessions thru Classes ( Not Code behind files) in ASP.NET application?

Select Answer:

• 1. Access in Classes

• 2. Set / Update in Classes

• 3. Both of above

• 4. None

Ans: 3

What is the Default ScriptTimeOut for Server Object?

Select Answer:

• 1. 30 Sec

• 2. 20 Sec

• 3. 60 Sec

• 4. 90 Sec


View State Concept based on

Select Answer:

• 1. HiddenField

• 2. PostBack

• 3. EventGeneration

• 4. ServerSide Controls

By default, when does validation automatically occur?

Select Answer:

• 1. After page initialization and before event handling

• 2. After page initialization and event handling

• 3. Before the data is sent to the server

• 4. Before page initialization and event handling

• 5. Any time an input control is changed


Which property of the Session object is used to set the local identifier?

Select Answer:

• 1. SessionID

• 2. LCID

• 3. Item

• 4. Key


What extension does the Web User Control file contain?

Select Answer:

• 1. .asmx

• 2. .ascx

• 3. .aspx

• 4. .awuc


To which namespaces do Trace and Debug belong?

Select Answer:

• 1. System.ComponentModel

• 2. System.Collections

• 3. System.Diagnostics

• 4. System.Trace

Ans: 3

Which control would you use if you needed to make sure the values in two different controls matched?

Select Answer:

• 1. Range Validator Control

• 2. Regular Expression Validator Control

• 3. Match Validator Control

• 4. CompareValidator Control

Ans: 4

What base class do all Web Forms inherit from?

Select Answer:

• 1. The System Class

• 2. The Inherit Class

• 3. The Page Class

• 4. The Global Class


How can you provide an alternating color scheme in a Repeater control?

Select Answer:

• 1. AlternatingItemTemplate

• 2. AlternateItemTemplate

• 3. AlternateTemplate

• 4. AlternatingTemplate


Which template must you provide, in order to display data in a Repeater control?

Select Answer:

• 1. DisplayTemplate

• 2. ShowTemplate

• 3. ItemTemplate

• 4. HeaderTemplate


what is a diffgram?

Select Answer:

• 1. Data Diagram

• 2. Data Dictionary

• 3. XML format

• 4. Diagram file


What type of code (server or client) is found in a Code-Behind class?

Select Answer:

• 1. Client-side code

• 2. Server-side code

• 3. Client-Server Code

• 4. None of the above


Which one of the following is NOT a valid state management tool?

Select Answer:

• 1. Hidden Form Fields

• 2. Cookies

• 3. Query State

• 4. Application State

• 5. Session State


Which DataTable property returns all rows and columns from a DataTable?

Select Answer:

• 1. TableView

• 2. ViewAll

• 3. DefaultView

• 4. ReturnTable


What is the purpose of code-behind?

Select Answer:

• 1. To separate different sections of a page into different files according to function

• 2. To merge layout HTML and the code into one file

• 3. To separate the layout HTML and the code into two different files

• 4. To discard the use of HTML


How to put conditional statement in Data Grid?

Select Answer:

• 1. Using Calling function in data grid only

• 2. Using ItemDataBound event only

• 3. Above both a and b.

• 4. Directly put condition in data grid


What are the default user directory permissions when a Web site is created in IIS?

Select Answer:

• 1. Read and Execute

• 2. Read and Write

• 3. Read/Write and Execute

• 4. Execute Only


An application using cookie authentication was working fine on another server. When moved to a new server, cookie authentication is not working correctly.
Which one of the following is the likely explanation of the above problem?

Select Answer:

• 1. The new IIS server is not configured to allow anonymous access

• 2. SSL is not properly configured.

• 3. The IP address of the new server does not match the prior server IP address

• 4. Passport authentication is not correctly configured.

• 5. The users are not correctly entering their passwords


How we can terminate the current session.

Select Answer:

• 1. Session.End

• 2. Session.Kill

• 3. Session.Abondon

• 4. We Can't Terminate the session


In global.asax file, which event will occur first when an application is invoked?

Select Answer:

• 1. Session_onStart()

• 2. Application_onStart()

• 3. Session_onEnd()

• 4. Application_onEnd()

• 5. None

Ans: 2

Which property indicates whether the control posts back to server each time a user interacts with a control?

Select Answer:

• 1. Post Back

• 2. Auto Post Back

• 3. Auto Event Wire Up

• 4. Trace


What are the minimum changes required for deploying an Application using xCopy deployment. where web site name will be change.

Select Answer:

• 1. Changes in web.Config Files

• 2. Changes in All Files and Build Application Again

• 3. Changes in the path of .SLN and webinfo.cs files.

• 4. changes in All configuration files and build Application again on the Destination Server.

• 5. None of Above


Which session state gives fastest application performance when we are maintaining sessions?
Fastest Mode in session states

Select Answer:

• 1. SqlServer

• 2. StateServer

• 3. InProc

• 4. Off


In which session state mode the session state will be disabled ?

Select Answer:

• 1. Inproc

• 2. StateServer

• 3. SqlServer

• 4. None of the Above


Threads are:
Threads are:

Select Answer:

• 1. static methods

• 2. objects

• 3. instance methods

• 4. events


What is the printout of the following?
What is the printout of the following?

byte b1=1;
byte b2=255;
byte total=b1+b2;
Console.WriteLine (total);

Select Answer:

• 1. We will get a runtime error

• 2. We will get a compilation error

• 3. 256

• 4. 1


Which of the following is true ?

Select Answer:

• 1. IsPostBack is a method of System.UI.Web.Page class

• 2. IsPostBack is a method of System.Web.UI.Page class

• 3. IsPostBack is a property of System.UI.Web.Page class

• 4. IsPostBack is a readonly property of System.Web.UI.Page class

• 5. IsPostBack is a static property of System.UI.Web.Page class


How you can dynamically change the background color of Datagrid cells.

Select Answer:

• 1. By Handling OnSelect event

• 2. By Handling Edit event

• 3. By Handling ItemBound event

• 4. By Handling PageChange event


The .NET class Global is derived from which of the following classes ?

Select Answer:

• 1. System.Web.UI.PageParser

• 2. System.Web.HttpApplicationState

• 3. System.Web.UI.Page

• 4. System.Web.HttpApplication

• 5. None of the above.

What is the function of Response.End?

Select Answer:

• 1. it will stop the server process

• 2. it will stop the client process

• 3. or both

• 4. or none


From which one of the following locations does the garbage collector remove objects?

Select Answer:

• 1. The download cache

• 2. The global assembly cache

• 3. The thread stack

• 4. The managed heap

• 5. The system registry

Ans: 4

What is Static and Dynamic Assemblies.?
The Difference between both.

Select Answer:

• 1. Both are same

• 2. There is no Static Assemblies

• 3. Dynamic assemblies have dynamic variable input but static assemblies have no variable input

• 4. Static Assemblies Define metadata and Dynamic assemblies Define Icon,String

• 5. Static Assemblies are created by user before running the application, Dynamic Assemblies are Dynamic


If one web form inherits the another web form, the drived web form able to access base class ....

Select Answer:

• 1. Code.

• 2. Server controls

• 3. HTML's

• 4. 1 and 2

• 5. all of above

Ans: 1

Technically,to whom we bind the any controls?

Select Answer:

• 1. Dataset

• 2. Datareader

• 3. Datatable

• 4. Dataview

Ans: 4

Which of the following controls contribute the highest Requests per second

Select Answer:

• 1. DataGrid

• 2. DataList

• 3. DataRepeater


User Control is nothing but

Select Answer:

• 1. A logical component

• 2. A visual component

• 3. Both of Logical and Visual

• 4. None of the above


What is boxing and unboxing ?
Implicit (manual) conversion of value type to reference type of a variable is known as BOXING, for example integer to object type conversion. Conversion of Boxed type variable back to value type is called as UnBoxing.

what is connected and diconnected database ?
Connected and Disconneted database basicallythe approch that how you handle the database connection, It may be connected that once the application starts you have to open the connection only for a single time and then performs many transactions and close the connection just before exit the application. This approch will be generally used in windows based application. On other hand disconnected architecter refere to open and close the connection for each time while performing a transactio.

What is garbage collection and how it works ?
Garbage Collection is Automatic Memory Manager for the dotnet framework. It manages the momery allocated to the .NET framework. CLR takes cares about .NET framework. When a variable is defined, Its gets a space in the memory and when the program control comes out of that function the scope of variable gets ended, so the garbage collection acts on and memory will releases.

What are the different types of caching ?
Output caching, Fragment Caching and Data caching.

What are different types of directives in .NET ?
Page, Outputcache, Register

1.What is the difference between user controls and custom controls?
CUSTOM CONTROLS are DLL'S.It can be placed in the toolbox.Drag and drop controls.
USER CONTROLS: are pages (.ascx).It can not be placed in the tool box.

2.what are the 3 types of session state modes?
a.Inproc-session kept as live object in the web server(aspnet_wp.exe)
b.Stateserver-Session serialized and stored in memory in a seperate process(aspnet_state.exe),we can use for webform architecture.
c.SQLServer-Session serialized and stored in sql server.

3. what are the 6 types of validation controls in ASP.NET?
1.Required Field validator.2.Range validator.3.Regular Expression validator.5custom validator.
6.validation summary.

4.What are the 3 types of caching in ASP.NET?
1. Output Caching(Page Caching)- stores the responses from an page(aspx) or user control(.ascx).
2.Fragment Caching(Partial Caching)- Only stores the portion of a page.
3. Data Caching is the programmatic way to your objects to a managed cache.
//Add item
Cache["TopProducts"] = objTopProductsDataset;
//Retrieve item
objDataset = Cache["TopProducts"];

.5.How to Manage state in ASP.NET?
we can manage the state in two ways
Clent based techniques are
Viewstate, Query strings and Cookies.
Server based techniques are
Application and Session

6.What is the difference between overloading and shadowing?
Overloading ----------- A Member has the name, but something else in the signature is different.
Shadowing --------- A member shadows another member if the derived member replaces the base member
7.what is the difference between overloading and overriding?
Overloading : Method name remains the same with different signatures.
Overriding : Method name and Signatures must be the same.
8.what is the difference between Manifest and Metadata?
Manifest describes assembly itself.
Assembly Name,version number,culture,strongname,listof all all files,Type references,and referenced assemblies.
Metadata describes contents in an assembly
classes, interfaces, enums, structs, etc., and their containing namespaces, the name of each type,
its visibility/scope, its base class, the interfaces it implemented, its methods and their scope
, and each method’s parameters, type’s properties, and so on.
9.What is Boxing and Unboxing?
Boxing is an implicit conversion of a value type to the type object
int i = 123; // A value type
Object box = i // Boxing
CASTING : casting is the process of converting a variable from one type to another (from a string to an integer )
Unboxing is an explicit conversion from the type object to a value type
int i = 123; // A value type
object box = i; // Boxing
int j = (int)box; // Unboxing

10.what are the method parameter in c#?
C# is having 4 parameter types which are
1.Value Parameter. default parameter type. Only Input
2.Reference(ref) Parameter. Input\Output
3.Output(out) Parameter.
4.Parameter(params) Arrays
11.what are value types and reference types?
Value type
bool, byte,chat, decimal,double,enum , float, int, long, sbyte, short, strut, uint, ulong, ushort
Value types are stored in the Stack
Reference type
class, delegate, interface, object, string
Reference types are stored in the Heap
12.what are the two activation modes for .NET Remoting?
1. Singleton 2. Singlecall

13.what's singlecall Activation mode used for ?
The Server Object is instantiated for responding to just one single request
14.what's the singleton Activation mode used for?
The server object is instantiated for responding number of clients
15.what are the channels and Formatters?
Binay Over TCP is most efficient
SOAP over HTTP is most interoperable
Binary and SOAP
16.What are the two Authentication modes for SQL server connection?
1. Trusted Connection - Windows Authentication
2. Non trusted Connection - Sql Server Authentication(its preferable for webservices)
17.What is typed dataset?
Data Access is normally done using indexes on collectionsin object model.
In ADO.NET it is possible to create a variation on a Dataset that does support
such syntax.Such Dataset is called "Typed Dataset".
Errors in the syntax are detected during compile time rather than runtime.
Advantages of Typed Dataset:
1.The data designer tool generates typed Datasets.
2.When we type the name of a dataset while writing a code,
weget a list of all available tables in the dataset.No need to
remember the table names.
For (eg) instead of typing
we can type

18.what is DataReader?

DataReader is a read only stream of data returned from
the database as the query executes.
It contains one row of data in memory at a time and is
restricted to navigating forward only in the results one record at a time.
Datareader supports access to multiple result sets but only one at a time and in the order retrieved.
In ADO data is no longer available through the Datareaderoncethe connection to the datasource is closed
which means a Datareader requires a connection to the Database throughout its usage.
o/p parameters or return values are only available thrugh the Datareader once the connection is closed.
19.Difference between Dataset and Recordset?
The Recordset was not XML-based and could not be serialized to XML easily or flexibly.
Finally, a Recordset was not independent of a data store because it tracked a Connection object
and through its methods could send queries to the data source to populate, update,
and refresh its data.
To that end, the Recordset contained functionality found in the ADO.NET DataSet,
data reader, and data adapter objects.

Similar to the DataSet, a Recordset could be disconnected from its data store
and therefore act as an in-memory cache of data.
Of course, it could also be used in a connected model depending on the cursor options that were set.
Although the Recordset object stored multiple versions of each column for each of its rows,
it was not by nature able to represent multiple tables without the use of the Data Shape Provider.
21.What isan Assembly, Private Assembly and SharedAssembly,Strong Name?
Assembly: Assemblies are basically the compiled code in .Net which contains the code in Microsoft Intermediate Langauge and one more thing that assembiles do for us as compared to dlls is they can maintain versioning with the help of the manifest.
You dont need to register the assemblies after compiling like we needed in dlls. you can put the assemblies in the bin folder and refer the namespaces from there.
In short find the assembly description as :
Assemblies are the building blocks of .NET Framework applications; they form the fundamental unit of deployment, version control, reuse, activation scoping, and security permissions. An assembly is a collection of types and resources that are built to work together and form a logical unit of functionality. An assembly provides the common language runtime with the information it needs to be aware of type implementations. To the runtime, a type does not exist outside the context of an assembly.

Private assembly is used inside an application only and does not have to be identified by a strong name
Shared assembly can be used by multiple applications and has to have a strong name.
Strong Name :A strong name includes the name of the assembly, version number, culture identity, and a public key token.

22.what is an Delegate?
A strongly typed function pointer. A delegate object encapsulates a reference to a method.
23.what are webservices?
A Web Service is an application that delivers a service across the Internet using the standards and technologies defined in the Web Services architecture in a platform-independent and language-neutral fashion.
Web Services rely on several XML protocols based on open standards that are collectively known as the Web Services architecture
24.Define Automatic memory Management:
c# Provides Automatic memory Management.
Automatic memory Management increases code quality and enhances developer productivity without negatively impacting
either expressivenessor perfromance.Developers are freed from this burdensome task.
25.Define Threading:
It's a process of creating applications that can perform multiple tasks independently.
26Difference Between XML AND HTML?
User definable tags.
Content driven
End tags required for well formed documents
Quotes required around attributes values
Slash required in empty tags
Defined set of tags designed for web display
Format driven
End tags not required
Quotes not required
Slash not required
27.What is XSLTand what is it's use?
XSL Transformations (XSLT) is yet another popular W3C specification that defines XML-based syntax, used to transform XML documents to any other text format, such as HTML, text, XML, etc. XSLT stylesheets can be applied on the source XML document to transform XML into some other XML, or text, HTML, or any other text format.

28.What is Diffgram?
It's an XML format.
It'sone of the two xml formats that uses to render Dataset object contents to XML.
For reading database data to an XML file to be sent to a webservice.
29.what is the Role of XSL?
Querying a database and then formatting the result set so that it can be validated as an XML document allows developers to translate the data into an HTML table using XSLT rules. Consequently, the format of the resulting HTML table can be modified without changing the database query or application code since the document rendering logic is isolated to the XSLT rules
30.What is SAX?
Simple API for XML Processing (SAX) is an alternative to DOM, and can be used to parse XML documents. SAX is based on streaming model. The SAX parser reads input XML stream and generates various parsing events that an application can handle. With each parsing event, the parser sends sufficient information about the node being parsed. Unlike DOM, SAX does not build an in-memory representation of the source XML document, and hence it is an excellent alternative when parsing large XML documents, as SAX does not require that much memory (and resources). Unlike DOM, SAX is not defined/controlled by W3C. See for details.

32.Give a few examples of types of applications that can benefit from using XML.
XML allows content management systems to store documents independently of their format, which thereby reduces data redundancy. Another answer relates to B2B exchanges or supply chain management systems. In these instances, XML provides a mechanism for multiple companies to exchange data according to an agreed upon set of rules. A third common response involves wireless applications that require WML to render data on hand held devices.

33.When constructing an XML DTD, how do you create an external entity reference in an attribute value?
when using SGML, XML DTDs don't support defining external entity references in attribute values.
34.Give some examples of XML DTDs or schemas that you have worked with.
Although XML does not require data to be validated against a DTD, many of the benefits of using the technology are derived from being able to validate XML documents against business or technical architecture rules. Polling for the list of DTDs that developers have worked with provides insight to their general exposure to the technology.commonly used DTDs such as FpML, DocBook, HRML, and RDF, as well as experience designing a custom DTD for a particular project
35.What is SOAP and how does it relate to XML?
The Simple Object Access Protocol (SOAP) uses XML to define a protocol for the exchange of information in distributed computing environments. SOAP consists of three components: an envelope, a set of encoding rules, and a convention for representing remote procedure calls. Unless experience with SOAP is a direct requirement for the open position, knowing the specifics of the protocol, or how it can be used in conjunction with HTTP, is not as important as identifying it as a natural application of XML.
36.What is WSDL?
Another key standard in the Web Services architecture is the Web Services Description Language, or WSDL for short. Whereas SOAP is responsible for providing a platform-neutral protocol for transporting data types and interapplication messaging, WSDL is an XML grammar responsible for exposing the methods, arguments, and return parameters exposed by a particular Web Service.

37.What’s the difference between authentication and authorization? Authentication happens first. You verify user’s identity based on credentials. Authorization is making sure the user only gets access to the resources he has credentials for.
38.Explain loosely coupled events. Loosely coupled events enable an object (publisher) to publish an event. Other objects (subscribers) can subscribe to an event. COM+ does not require publishers or subscribers to know about each other. Therefore, loosely coupled events greatly simplify the programming model for distributed applications.
39.Define scalability.
The application meets its requirement for efficiency even if the number of users increases.
40.Define reliability.
The application generates correct and consistent information all the time.
41.Define availability.
Users can depend on using the application when needed.
42.Define security.
The application is never disrupted or compromised by the efforts of malicious or ignorant users
43.Define manageability.
Deployment and maintenance of the application is as efficient and painless as possible
44.Explain durability.
Make sure that the system can return to its original state in case of a failure.
45.Explain integrity.
Ensure data integrity by protecting concurrent transactions from seeing or being adversely affected by each other’s partial and uncommitted results.
46.Explain consistency.
We must ensure that the system is always left at the correct state in case of the failure or success of a transaction.
47.Explain JIT activation.
The objective of JIT activation is to minimize the amount of time for which an object lives and consumes resources on the server. With JIT activation, the client can hold a reference to an object on the server for a long time, but the server creates the object only when the client calls a method on the object. After the method call is completed, the object is freed and its memory is reclaimed. JIT activation enables applications to scale up as the number of users increases
48.Define Constructors and destructors
The create and destroy methods - often called constructors and destructors - are usually implemented for any abstract data type. Occasionally, the data type's use or semantics are such that there is only ever one object of that type in a program. In that case, it is possible to hide even the object's `handle' from the user. However, even in these cases, constructor and destructor methods are often provided.
Of course, specific applications may call for additional methods, e.g. we may need to join two collections (form a union in set terminology) - or may not need all of these.

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