General Questions
1. Does C# support multiple-inheritance?
No.
2. Who is a protected class-level variable available to?
It is available to any sub-class (a class inheriting this class).
3. Are private class-level variables inherited?
Yes, but they are not accessible. Although they are not visible or
accessible via the class interface, they are inherited.
4. Describe the accessibility modifier “protected internal”.
It is available to classes that are within the same assembly and derived
from the specified base class.
5. What’s the top .NET class that everything is derived from?
ystem.Object.
6. What does the term immutable mean?
The data value may not be changed. Note: The variable value may be
changed, but the original immutable data value was discarded and a
new data value was created in memory.
7. What’s the difference between System.String and
System.Text.StringBuilder classes?
ystem.String is immutable. ystem.StringBuilder was designed with
the purpose of having a mutable string where a variety of operations
can be performed.
8. What’s the advantage of using System.Text.StringBuilder over
System.String?
StringBuilder is more efficient in cases where there is a large amount of
string manipulation. Strings are immutable, so each time a string is
changed, a new instance in memory is created.
9. Can you store multiple data types in System.Array?
No.
10. What’s the difference between the System.Array CopyTo() and
System Array.Clone()?
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. A shallow copy means the contents (each array element) contains
references to the same object as the elements in the original array. A
deep copy (which neither of these methods performs) would create a
new instance of each element's object, resulting in a different, yet
identacle object.
11. How can you sort the elements of the array in descending order?
By calling Sort() and then Reverse() methods.
12. What’s the .NET collection class that allows an element to be
accessed using a unique key?
HashTable.
13. What class is underneath the SortedList class?
A sorted HashTable.
14. Will the finally block get executed if an exception has not
occurred?
Yes.
15. What’s the C# syntax to catch any possible exception?
A catch block that catches the exception of type ystem.Exception. You
can also omit the parameter data type in this case and just write catch
{}.
16. Can multiple catch blocks be executed for a single try
statement?
No. Once the proper catch block processed, control is transferred to the
finally block (if there are any).
17. Explain the three services model commonly know as a three-tier
application
Presentation (UI), Business (logic and underlying code) and Data (from
storage or other sources).
Class Questions
1. What is the syntax to inherit from a class in C#?
Place a colon and then the name of the base class.
Example: class MyNewClass : MyBaseClass
2. Can you prevent your class from being inherited by another
class?
Yes. The keyword “sealed” will prevent the class from being inherited.
3. Can you allow a class to be inherited, but prevent the method
from being over-ridden?
Yes. Just leave the class public and make the method sealed.
4. What’s an abstract class?
A class that cannot be instantiated. An abstract class is a class that
must be inherited and have the methods overridden. An abstract class
is essentially a blueprint for a class without any implementation.
5. When do you absolutely have to declare a class as abstract?
1. When the class itself is inherited from an abstract class, but not all
base abstract methods have been overridden.
2. When at least one of the methods in the class is abstract.
6. What is an interface class?
Interfaces, like classes, define a set of properties, methods, and events.
But unlike classes, interfaces do not provide implementation. They are
implemented by classes, and defined as separate entities from classes.
7. Why can’t you specify the accessibility modifier for methods
inside the interface?
They all must be public, and are therefore public by default.
8. Can you inherit multiple interfaces?
Yes. .NET does support multiple interfaces.
9. What happens if you inherit multiple interfaces and they have
conflicting method names?
It’s up to you to implement the method inside your own class, so
implementation is left entirely up to you. This might cause a problem on
a higher-level scale if similarly named methods from different interfaces
expect different data, but as far as compiler cares you’re okay.
To Do: Investigate
10. What’s the difference between an interface and abstract class?
In an interface class, all methods are abstract - there is no
implementation. In an abstract class some methods can be concrete.
In an interface class, no accessibility modifiers are allowed. An
abstract class may have accessibility modifiers.
11. What is the difference between a Struct and a Class?
Structs are value-type variables and are thus saved on the stack,
additional overhead but faster retrieval. Another difference is that
structs cannot inherit.
Method and Property Questions
1. What’s the implicit name of the parameter that gets passed into
the set method/property of a class?
Value. The data type of the value parameter is defined by whatever
data type the property is declared as.
2. What does the keyword “virtual” declare for a method or
property?
The method or property can be overridden.
3. How is method overriding different from method overloading?
When overriding a method, you change the behavior of the method for
the derived class. Overloading a method simply involves having
another method with the same name within the class.
4. Can you declare an override method to be static if the original
method is not static?
No. The signature of the virtual method must remain the same. (Note:
Only the keyword virtual is changed to keyword override)
5. What are the different ways a method can be overloaded?
Different parameter data types, different number of parameters,
different order of parameters.
6. If a base class has a number of overloaded constructors, and
an inheriting class has a number of overloaded constructors; can
you enforce a call from an inherited constructor to a specific
base constructor?
Yes, just place a colon, and then keyword base (parameter list to invoke
the appropriate constructor) in the overloaded constructor definition
inside the inherited class.
Events and Delegates
1. What’s a delegate?
A delegate object encapsulates a reference to a method.
2. What’s a multicast delegate?
A delegate that has multiple handlers assigned to it. Each assigned
handler (method) is called.
XML Documentation Questions
1. Is XML case-sensitive?
Yes.
2. What’s the difference between // comments, /* */ comments
and /// comments?
Single-line comments, multi-line comments, and XML documentation
comments.
3. How do you generate documentation from the C# file
commented properly with a command-line compiler?
Compile it with the /doc switch.
Debugging and Testing Questions
1. What debugging tools come with the .NET SDK?
1. CorDBG – command-line debugger. To use CorDbg, you must
compile the original C# file using the /debug switch.
2. DbgCLR – graphic debugger. Visual Studio .NET uses the DbgCLR.
2. What does assert() method do?
In debug compilation, assert takes in a Boolean condition as a
parameter, and shows the error dialog if the condition is false. The
program proceeds without any interruption if the condition is true.
3. What’s the difference between the Debug class and Trace class?
Documentation looks the same. Use Debug class for debug builds, use
Trace class for both debug and release builds.
4. Why are there five tracing levels in
System.Diagnostics.TraceSwitcher?
The tracing dumps can be quite verbose. For applications that are
constantly running you run the risk of overloading the machine and the
hard drive. Five levels range from None to Verbose, allowing you to
fine-tune the tracing activities.
5. Where is the output of TextWriterTraceListener redirected?
To the Console or a text file depending on the parameter passed to the
constructor.
6. How do you debug an ASP.NET Web application?
Attach the aspnet_wp.exe process to the DbgClr debugger.
7. What are three test cases you should go through in unit testing?
1. Positive test cases (correct data, correct output).
2. Negative test cases (broken or missing data, proper handling).
3. Exception test cases (exceptions are thrown and caught
properly).
8. Can you change the value of a variable while debugging a C#
application?
Yes. If you are debugging via Visual Studio.NET, just go to Immediate
window.
ADO.NET and Database Questions
1. What is the role of the DataReader class in ADO.NET
connections?
It returns a read-only, forward-only rowset from the data source. A
DataReader provides fast access when a forward-only sequential read is
needed.
2. What are advantages and disadvantages of Microsoft-provided
data provider classes in ADO.NET?
SQLServer.NET data provider is high-speed and robust, but requires
SQL Server license purchased from Microsoft. OLE-DB.NET is universal
for accessing other sources, like Oracle, DB2, Microsoft Access and
Informix. OLE-DB.NET is a .NET layer on top of the OLE layer, so it’s
not as fastest and efficient as qlServer.NET.
3. What is the wildcard character in SQL?
Let’s say you want to query database with LIKE for all employees whose
name starts with La. The wildcard character is %, the proper query with
LIKE would involve ‘La%’.
4. Explain ACID rule of thumb for transactions
A transaction must be:
1. Atomic - it is one unit of work and does not dependent on
previous and following transactions.
2. Consistent - data is either committed or roll back, no “in-
between” case where something has been updated and something
hasn’t.
3. Isolated - no transaction sees the intermediate results of the
current transaction).
4. Durable - the values persist if the data had been committed even
if the system crashes right after.
5. What connections does Microsoft SQL Server support?
Windows Authentication (via Active Directory) and QL Server
authentication (via Microsoft SQL Server username and password).
6. Between Windows Authentication and SQL Server
Authentication, which one is trusted and which one is
untrusted?
Windows Authentication is trusted because the username and password
are checked with the Active Directory, the QL Server authentication is
untrusted, since SQL Server is the only verifier participating in the
transaction.
7. What does the Initial Catalog parameter define in the connection
string?
The database name to connect to.
8. What does the Dispose method do with the connection object?
Deletes it from the memory.
To Do: answer better. The current answer is not entirely correct.
9. What is a pre-requisite for connection pooling?
Multiple processes must agree that they will share the same connection,
where every parameter is the same, including the security settings.
The connection string must be identical.
Assembly Questions
1. How is the DLL Hell problem solved in .NET?
Assembly versioning allows the application to specify not only the
library it needs to run (which was available under Win32), but also the
version of the assembly.
2. What are the ways to deploy an assembly?
An M I installer, a CAB archive, and XCOPY command.
3. What is a satellite assembly?
When you write a multilingual or multi-cultural application in .NET, and
want to distribute the core application separately from the localized
modules, the localized assemblies that modify the core application are
called satellite assemblies.
4. What namespaces are necessary to create a localized
application?
ystem.Globalization and ystem.Resources.
5. What is the smallest unit of execution in .NET?
an Assembly.
6. When should you call the garbage collector in .NET?
As a good rule, you should not call the garbage collector. However,
you could call the garbage collector when you are done using a large
object (or set of objects) to force the garbage collector to dispose of
those very large objects from memory. However, this is usually not a
good practice.
7. How do you convert a value-type to a reference-type?
Use Boxing.
8. What happens in memory when you Box and Unbox a value-
type?
Boxing converts a value-type to a reference-type, thus storing the
object on the heap. Unboxing converts a reference-type to a value-
type, thus storing the value on the stack.
1. Explain the differences between Server-side and Client-side code?
ANS: Server side code will execute at server end all the business logic will
execute at server end where as client side code will execute at client side
at browser end.
2. What type of code (server or client) is found in a Code-Behind class?
AN : Server side.
3. Should validation (did the user enter a real date) occur server-side or
client-side? Why?
AN : client side . there is no need to go to validate user input. If it
relates to data base validation we need to validate at server side.
4. What does the "EnableViewState" property do? Why would I want it on
or off?
ANS: IT keeps the data of the control during post backs.
if we turn off the values should not populate during server round trip.
5. What is the difference between Server.Transfer and
Response.Redirect? Why would I choose one over the other?
ANS: Server.Trnasfer will prevent round trip. it will redirect pages which or
in the same directory. NO way to pass the query strings . Thru http
context we can able to get the previous page control values.
Response.Redirect : There is a round trip to process the request. We can
redirect to any page external / internal other than aspx. We can pass the
query string thru which we can manage sessions.
6. Can you give an example of when it would be appropriate to use a web
service as opposed to a non-serviced .NET component
AN : Web services are best suite for Hetrogenious environment.
Remoting is best suite for Homogenious environment. The systems that
under CLR.
7. Let's say I have an existing application written using Visual Studio 6
(VB 6, InterDev 6) and this application utilizes Windows 2000 COM+
transaction services. How would you approach migrating this
application to .NET
We need to have Wrapper to communicate COM components in .net. and
vis versa
CCW : Com Callable wrapper.
RCW : RUN time callable wrapper.
8. Can you explain the difference between an ADO.NET Dataset and
anADO Recordset?\
AN : DIsconnected architechure . Maintainace relation schemas. MUtilple
table grouping.
Connected one .
9. Can you give an example of what might be best suited to place in the
Application_Start and ession_Start subroutines?
ANS: APplication_start need for global variable which are available over
the application.
Sesssion_Start : login dependent ( user dependent)
10. If I'm developing an application that must accomodate multiple
security levels though secure login and my ASP.NET web appplication is
spanned across three web-servers (using round-robbin load balancing)
what would be the best approach to maintain login-in state for the
users?
AN : Database Support.
or Thru state service.
11. What are ASP.NET Web Forms? How is this technology different than
what is available though A P (1.0-3.0)?
AN : A P . Interprepter.. use the script engine.
ASP.Net Compiled.
12. How does VB.NET/C# achieve polymorphism?
AN : Function overloading.
Operator overloading.
11. Can you explain what inheritance is and an example of when you
might use it?
AN : Heridity.
Use the existing functionality along with its own properities.
13. How would you implement inheritance using VB.NET/C#?
ANS: Derived Class : Basecalss
VB.NEt : Derived Class Inherits Baseclass
14. Whats an assembly
AN : A Basic unit of executable code >
Which contains : Manifest - Meta data
versioning , Calture , IL, Reference
15. Describe the difference between inline and code behind - which is best
in a loosely coupled solution
Tightly coupled - INLINE
ANS: inline function bind at compile time can write in aspx page with in
<% %> .
17. Explain what a diffgram is, and a good use for one
AN : is an xml grammer. it talk about state of node in xml file.
18. Where would you use an iHTTPModule, and what are the limitations of
any approach you might take in implementing one
ANS: Preprocessing before going to II .
20. What are the disadvantages of viewstate/what are the benefits
AN : IT can be hacked . page is size is heavy.
21 Describe session handling in a webfarm, how does it work and what
are the limits
ANS:
Session - mode
State sever
OUtprocess
sql
22. How would you get ASP.NET running in Apache web servers - why
would you even do this?
ANS: ---- Install Mod_AspDotNet
Add at the end of C:\Program Files\Apache
Group\Apache2\conf\httpd.conf the following lines
23. Whats MSIL, and why should my developers need an appreciation of it
if at all?
AN : Microsoft Intermeidate lanaguage. which is the out put for all the
.net supported languages after comiplation will produce.
Appreciation for cross language support.
24. In what order do the events of an ASPX page execute. As a developer
is it important to undertsand these events?
AN : INIT, PageLoad, Prerender , UNload.
25. Which method do you invoke on the DataAdapter control to load your
generated dataset with data?
Fill()
26. Can you edit data in the Repeater control?
NO
27. Which template must you provide, in order to display data in a
Repeater control?
ITemtemplate
28. How can you provide an alternating color scheme in a
Repeatercontrol?
AlternateItemTemplate
29. What property must you set, and what method must you call in your
code, in order to bind the data from some data source to the
Repeatercontrol?
Datasource,
DataBind
30. What base class do all Web Forms inherit from?
ystem.Web.UI.Page
31. What method do you use to explicitly kill a user s session?
abondon()
32 How do you turn off cookies for one page in your site?
disablecookies.
33. Which two properties are on every validation control?
control to validate, error message
34. What tags do you need to add within the asp:datagrid tags to bind
columns manually?
autogenerated columns is set to false
35. How do you create a permanent cookie?
Cooke = ne cookee().
cooke.adddate.
36. What tag do you use to add a hyperlink column to the DataGrid?
hyper link column
37. What is the standard you use to wrap up a call to a Web service
------------
38. Which method do you use to redirect the user to another page without
performing a round trip to the client?
server.transfer
39. What is the transport protocol you use to call a Web service SOAP
http
40. True or False: A Web service can only be written in .NET
false
41. What does WSDL stand for?
webservice discription language. it is
used to generate for proxy( server object)
42. What property do you have to set to tell the grid which page to go to
when using the Pager object?
Page Index.
43. Where on the Internet would you look for Web services?
UDDI
44. What tags do you need to add within the asp:datagrid tags to bind
columns manually.
Autogenerate columns
45. Which property on a Combo Box do you set with a column name, prior
to setting the DataSource, to display data in the combo box?
datatext
datavalue
46. How is a property designated as read-only?
get
47. Which control would you use if you needed to make sure the values in
two different controls matched?
compare filed validator
48. True or False: To test a Web service you must create a windows
application or Web application to consume this service?
no
49. How many classes can a single .NET DLL contain?
as many as u want..
C#, ASP.NET, ADO.NET, XML:
? How many types of JIT compilers are available?
[Rama Naresh Talluri]
There are Two types of JIT compilers.
? standard JIT compiler.
? EconoJIT compiler.
? What are the different types of assemblies – name them?
[Rama Naresh Talluri]
Private
Public/Shared
Satellite assembly
? What is GAC? What are the steps to be taken to pick up the latest version
from GAC?
[Rama Naresh Talluri]
This Global Assembly Cache(GAC) stores .NET assemblies to be shared by
several applications on that computer.
publisher policy file is the configuration file to redirect to different version
1. Create the publisher Policy assembly using the assembly linker
2. Add the publisher policy assembly to the GAC using GACutil tool
Gacutil /i
3. During runtime CLR is looking into the publisher policy file and redirect the
application to bind with new version assembly as specified inside the
publisher policy.
? How do we use different versions of private assemblies in same application
without re-build?
[Rama Naresh Talluri]
In Asseblyinfo file need specify assembly version.
assembly: AssemblyVersion
? Different methods of using a legacy COM component in .NET framework?
[Rama Naresh Talluri]
1. TLBIMP to create an Assembly from a COM component
2. Reference a COM component directly from .NET Editor
? How do you implement SL?
[Rama Naresh Talluri]
1. create certificate request
[
=>Right click on the website (VD)
=>Click Directory Security Tab and click Server Certificate
=> Type name of certificate , Organization name , server name
location info,
=> Type the path need to save certificate information Submit certificate
request.
]
2.Submit Certificate request.
[
=> Browse http://Web erverName/CertSrv/
=> select Request a Certificate and click Next
=> select Advanced Request and click Next
=> select Submit a Certificate Request using a Base64 and click Next
=> open the request document "Create a certificate request" section
=> Copy the contents of the document
=> Paste the contents of the document into the Web form's Base64 Encoded
Certificate Request text box
=> Under Certificate Template, select Web Server or User, and then click
Submit
]
? Is it possible to debug java-script in .NET IDE? If yes, how?
[Rama Naresh Talluri]
Yes. Write debugger statement to stop the cursor for debugging .
? How do you create a webservice proxy without .NET IDE and how do you
test it?
[Rama Naresh Talluri]
wsdl utility we can test by consuming our service either windows / web
application
? How to debug an assembly which is on erver?
[Rama Naresh Talluri]
[assembly: AssemblyDescription("Debug")]
? How many ways can we maintain the state of a page?
[Rama Naresh Talluri]
1.Client Side [ Query string, hidden variables, view state,cookies]
2.Server side [application , session, database]
? How do we Generate and compile source code dynamically?
[Rama Naresh Talluri]
.Net provides powerful access to the IL code generation process through the
ystem.CodeDom.Compiler and Microsoft.CSharp and Microsoft.VisualBasic
namespaces. In these namespaces we can find the tools that allow us to
compile an assembly either to disk or into memory. We can also need the
Reflection namespace as it contains the tools to invoke an object and its
methods once we have compiled the object.
? How to pass server control values from one form to another using in-line
code?
[Rama Naresh Talluri]
Server.Transfer
? How to make a webservice call asynchronous?
[Rama Naresh Talluri]
//Create a new instance of the Web Service Class
localhost.Service1 service = new MyWeb erviceApp.localhost.Service1();
//Make the asynchronous Web ervice call and call WriteHello
service.BeginHelloWorld(new ystem.AsyncCallback (WriteHello), service);
private void WriteHello( ystem.IAsyncResult oRes)
{
//End the call
localhost.Service1 service = (MyWeb erviceApp.localhost.Service1)
oRes.AsyncState;
//Write the call result to a MessageBox
MessageBox.Show(service.EndHelloWorld(oRes));
}
? How to invoke a webservice using javascript?
[Rama Naresh Talluri]
? List out all the possible ways of maintaining the state of a session.
[Rama Naresh Talluri]
InProc
OutProc [State server, sql]
? What is the use of multicast delegate?
[Rama Naresh Talluri]
A multicast delegate can call more than one method.
? What is the purpose of a private constructor?
[Rama Naresh Talluri]
Prevent the creation of instance for a class
? Differentiate Dispose and Finalize.
[Rama Naresh Talluri]
Finalize is called by the Garbage Collector, and the state of manage objects
cannot be guaranteed, so we can not reference them. Also, we cannot
determine when the GC will run, and which objects it will Finalize.
Dispose is called by the programmer, and is used to dispose of managed and
unmanaged objects. Within we dispose method, we release all of our
resources and call GC. uppressFinalize as we have done the work of the GC.
? What is the purpose of Singleton pattern?
[Rama Naresh Talluri]
Singleton pattern is used to make sure that only one instance of a given class
exists.
? Difference between structure and class.
[Rama Naresh Talluri]
Structures are value types;
classes are reference types.
Structures use stack allocation;
classes use heap allocation.
All structure elements are Public by default;
class variables and constants are Private by default, while other class
members are Public by default.
Structure elements cannot be declared as Protected; class members can.
Structure variable declarations cannot specify initializers or initial sizes for
arrays; class variable declarations can.
Structures implicitly inherit from the ystem.ValueType class and cannot
inherit from any other type;
classes can inherit from any class or classes other than ystem.ValueType.
Structures are not inheritable; classes are.
Structures are never terminated, so the common language runtime (CLR)
never calls the Finalize method on any structure; classes are terminated by
the garbage collector (GC), which calls Finalize on a
class when it detects there are no active references remaining.
? Difference between DOM and AX parser.
[Rama Naresh Talluri]
DOM Approach is useful for small documents in which the program needs to
process a large portion of the document.
AX approach is useful for large documents in which the program only needs
to process a small portion of the document
AX parsers generally requires more code than the DOM interface.
Unless we build a DOM style tree from our application's internal
representation for the data, we can't as easily write the XML file back to disk.
The DOM tree is not constructed, so there are potentially less memory
allocation.
If we convert the data in the DOM tree to another format, the AX API may
help to remove the intermediate step
If we do not need all the XML data in memory, the AX API allows us to
process the data as it is parsed
? Under what circumstances do you use DOM parser and AX parser
[Rama Naresh Talluri]
DOM Approach is useful for small documents in which the program needs to
process a large portion of the document.
AX approach is useful for large documents in which the program only needs
to process a small portion of the document
If we do not need all the XML data in memory, the AX API allows us to
process the data as it is parsed
? What is a well-formed XML and is the purpose of Diffgram?
[Rama Naresh Talluri]
A textual object is a well-formed XML document if it satisfies all the following
points
1. Taken as a whole, it matches the production labeled document.
2. It meets all the well-formedness constraints given in this specification.
3. Each of the parsed entities which is referenced directly or indirectly within
the document is well-formed.
The purpose of Diffgram is the Ability to pass parameters. It contains the
tags that specify the original and new state of data
? Differentiate between legacy ADO recordset and .NET dataset.
What are typed datasets.
[Rama Naresh Talluri]
Recordset provides data one row at a time.
Connection is open .
Dataset is a data structure which represents the complete table data at same
time.
Dataset is just a data store and manipulation is done through DataAdapters
in .NET
Typed DataSets generate classes that expose each object the in the DataSet
in Type-safe manner. It will raise error at compile time if any mismatch of
column data type.
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