2008 March 14 « My Digital Life

March 14, 2008

>Net

Filed under: plcement paper — colwmk @ 9:31 pm

What is the base class of .NET?Explain assemblies
Base class provides a base set of methods that all derived classes can use

Explain assemblies
Answer 1:
Assemblies are similar to dll files. Both has the reusable pieces of code in the form of classes/ functions. Dll needs to be registered but assemblies have its own metadata.

Answer 2:
Assembly is a single deployable unit that contains information about the implementation of classes, structures and interfaces. it also stores the information about itself called metadata and includes name and verison of the assembly, security information, information about the dependencies and the list of files that constitute the assembly.
Assembly also contains namespaces. In the .Net Framework, applications are deployed in the form of assemblies.

Answer 3:
An assembly is a single deployable unit that contains all the information about the implementation of :
- classes
- structures and
- interfaces

An assembly stores all the information about itself. This information is called METADATA and include the name and the verison number of the assembly, security information, information about the dependencies and a lost of files that constitute the assembly.
All the application developed using the .NET framework are made up of assemblies.
Namespaces are also stored in assemblies

Answer 4:
In theMicrosoft .NET framework an assembly is a partially compiled code library for use in deployment, versioning and security. In the Microsoft Windows implementation of .NET, an assembly is a PE (portable executable) file. There are two types, process assemblies (EXE) and library assemblies (DLL). A process assembly represents a process which will use classes defined in library assemblies. In version 1.1 of the CLR classes can only be exported from library assemblies; in version 2.0 this restriction is relaxed. The compiler will have a switch to determine if the assembly is a process or library and will set a flag in the PE file. .NET does not use the extension to determine if the file is a process or library. This means that a library may have either .dll or .exe as its extension.

The code in an assembly is partially compiled into CIL, which is then fully compiled into machine language at runtime by the CLR.

An assembly can consist of one or more files. Code files are called modules. An assembly can contain more than one code module and since it is possible to use different languages to create code modules this means that it is technically possible to use several different languages to create an assembly. In practice this rarely happens, principally because Visual Studio only allows developers to create assemblies that consist of a single code module.

Name some of the languages .NET support?
Some of the languages that are supported by .NET
1. Visual Basic.NET
2. Visual C#
3. Visual C++

ADO.NET features? Benefits? Drawbacks?
Answer 1:
1. Data will be retrieved through Datasets
2. Scalability

Answer 2:
1. Disconnected Data Architecture
2. Data cached in Datasets
3. Data transfer in XML format
4. Interaction with the database is done through data commands

How many types of exception handlers are there in .NET?
Answer 1:
From
MSDN>gt; “How the Runtime Manages Exceptions”
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconexceptionsoverview.asp
The exception information table represents four types of exception handlers for protected blocks:
A finally handler that executes whenever the block exits, whether that occurs by normal control flow or by an unhandled exception.
A fault handler that must execute if an exception occurs, but does not execute on completion of normal control flow.
A type-filtered handler that handles any exception of a specified class or any of its derived classes.
A user-filtered handler that runs user-specified code to determine whether the exception should be handled by the associated handler or should be passed to the next protected block.

Answer 2:
1. Unstructured Exception Handling
2. Structured Exception Handling

Difference between Panel and GroupBox classes?

Answer 1:
Panel and Group box both can used as container for other controls like radio buttons and check box.
the difference in panel and group box are Panel
1) In case of panel captions cannot be displayed
2) Can have scroll bars.

Group box
1) Captions can be displayed.
2) Cannot have a scroll bar

Answer 2:
Panel is scrollable. In panel you can’t set caption like Group box.

What is the base class of Button control?
Listing from visual studio .net > Button Class
System.Object
System.MarshalByRefObject
System.ComponentModel.Component
System.Windows.Forms.Control
System.Windows.Forms.ButtonBase
System.Windows.Forms.Button

What is Response object? How is it related to ASP’s Response object?
Response object allows the server to communicate with the client(browser). It is useful for displaying information to the user (or) redirecting the client.
Eg: Response.Write(”Hello World”)

hat is IIS? Have you used it?
IIS – Internet Information Server
IIS is used to access the ASP.Net web applications
Yes, I used in ASP.NET web applications.

Main differences between ASP and ASP.NET.
Answer 1:
1. ASP: Code is Interpreted
ASP.NET: Code is Compiled

2. ASP: Business Logic and Presentation Logic are in a single file
ASP.NET: Business Logic and Presentation Logic are in separate files (.cs or .vb) and (.aspx) respectively.
3. ASP: No Web Server Controls
ASP.NET: Web Server Controls supported by strong .NET Framework
4. ASP: No RAD in Classic ASP
ASP.NET: Supports RAD

Answer 2:
1.Asp is interpreted
Asp.net is compiled which is faster than asp.
2 Asp.net maintains its own CLR and is managed as it runs by CLR
Where as asp is unmanaged
3 We can mainatin sessions in state server and sql server which is Outproc,
where in asp sessions will be last if we restart webserver or make changes.
4 In asp.net we can configure each application using web.config file which is availble in application itself and we have machine.config wherer we can configure all applications.
In asp we cannot configure single aplication
5 Asp.net we have autopostback event which is not in asp
6 In asp.net we have global.asax where can hadle some global things which is not in asp.
7 We have well built GUI to work in asp.net
8 We have ado.net and as well as disconnected architecture in asp.net
9 We have Xcopy deployment in asp.net
10. We can work with any language as code behind technique in asp.net that supports .net frame work

Answer 3:
a) asp.net is compiled but ASP is a interpretor or script only.
b) asp.net is supported more control then the asp.
c) asp.net is more supported even control then the asp.
d) In asp.net if update any component then no need to shutdown the computer but in asp if loaded any component then need tobe shutdown the computer.
d) So lastly an asp.net is faster then asp .

What are the advantages and drawbacks of using ADO.NET?

Pros

ADO.NET is rich with plenty of features that are bound to impress even the most skeptical of programmers. If this weren’t the case, Microsoft wouldn’t even be able to get anyone to use the Beta. What we’ve done here is come up with a short list of some of the more outstanding benefits to using the ADO.NET architecture and the System.Data namespace.

* Performance – there is no doubt that ADO.NET is extremely fast. The actual figures vary depending on who performed the test and which benchmark was being used, but ADO.NET performs much, much faster at the same tasks than its predecessor, ADO. Some of the reasons why ADO.NET is faster than ADO are discussed in the ADO versus ADO.NET section later in this chapter.

* Optimized SQL Provider – in addition to performing well under general circumstances, ADO.NET includes a SQL Server Data Provider that is highly optimized for interaction with SQL Server. It uses SQL Server’s own TDS (Tabular Data Stream) format for exchanging information. Without question, your SQL Server 7 and above data access operations will run blazingly fast utilizing this optimized Data Provider.

* XML Support (and Reliance) – everything you do in ADO.NET at some point will boil down to the use of XML. In fact, many of the classes in ADO.NET, such as the DataSet, are so intertwined with XML that they simply cannot exist or function without utilizing the technology. You’ll see later when we compare and contrast the “old” and the “new” why the reliance on XML for internal storage provides many, many advantages, both to the framework and to the programmer utilizing the class library.

* Disconnected Operation Model – the core ADO.NET class, the DataSet, operates in an entirely disconnected fashion. This may be new to some programmers, but it is a remarkably efficient and scalable architecture. Because the disconnected model allows for the DataSet class to be unaware of the origin of its data, an unlimited number of supported data sources can be plugged into code without any hassle in the future.

* Rich Object Model – the entire ADO.NET architecture is built on a hierarchy of class inheritance and interface implementation. Once you start looking for things you need within this namespace, you’ll find that the logical inheritance of features and base class support makes the entire system extremely easy to use, and very customizable to suit your own needs. It is just another example of how everything in the .NET framework is pushing toward a trend of strong application design and strong OOP implementations.

Cons

Hard as it may be to believe, there are a couple of drawbacks or disadvantages to using the ADO.NET architecture. I’m sure others can find many more faults than we list here, but we decided to stick with a short list of some of the more obvious and important shortcomings of the technology.

* Managed-Only Access – for a few obvious reasons, and some far more technical, you cannot utilize the ADO.NET architecture from anything but managed code. This means that there is no COM interoperability allowed for ADO.NET. Therefore, in order to take advantage of the advanced SQL Server Data Provider and any other feature like DataSets, XML internal data storage, etc, your code must be running under the CLR.

* Only Three Managed Data Providers (so far) – unfortunately, if you need to access any data that requires a driver that cannot be used through either an OLEDB provider or the SQL Server Data Provider, then you may be out of luck. However, the good news is that the OLEDB provider for ODBC is available for download from Microsoft. At that point the down-side becomes one of performance, in which you are invoking multiple layers of abstraction as well as crossing the COM InterOp gap, incurring some initial overhead as well.

* Learning Curve – despite the misleading name, ADO.NET is not simply a new version of ADO, nor should it even be considered a direct successor. ADO.NET should be thought of more as the data access class library for use with the .NET framework. The difficulty in learning to use ADO.NET to its fullest is that a lot of it does seem familiar. It is this that causes some common pitfalls. Programmers need to learn that even though some syntax may appear the same, there is actually a considerable amount of difference in the internal workings of many classes. For example (this will be discussed in far more detail later), an ADO.NET DataSet is nothing at all like a disconnected ADO RecordSet. Some may consider a learning curve a drawback, but I consider learning curves more like scheduling issues. There’s a learning curve in learning anything new; it’s just up to you to schedule that curve into your time so that you can learn the new technology at a pace that fits your schedule.

Why The JavaScript Validation Not Run on the Asp.Net Button But Run SuccessFully On The HTML Button
The Asp.Net Button Is post backed on the server & not yet Submit & when It goes to the server its states is lost So if we r using javascript in our application so we always use the Input Button in the asp Button

what is the difference between user control an custom control? advantages/disadvantages?
Web user controls Vs Web custom controls
Easier to create Vs Harder to create
Limited support for consumers who use a visual design tool Vs Full visual design tool support for consumers
A separate copy of the control is required in each application Vs Only a single copy of the control is required, in the global assembly cache
Cannot be added to the Toolbox in Visual Studio Vs Can be added to the Toolbox in Visual Studio
Good for static layout Vs Good for dynamic layout

What’s the difference between Response.Write() andResponse.Output.Write()?
Response.Output.Write() allows you to write formatted output

What is the use of ErrorProvider Control?
The ErrorProvider control is used to indicate invalid data on a data entry form. Using this control, you can attach error messagesthat display next to the control when the data is invalid, as seen in the following image. A red circle with an exclamation point blinks, and when the user mouses over the icon, the error message is displayed as a tooltip.

What is CLR?
Answer 1:
CLR(Common Language Runtime) is the main resource of .Net Framework. it is collection of services like garbage collector, exception handler, jit compilers etc. with the CLR cross language integration is possible.

Answer 2:
The .NET Framework provides a runtime environment which runs the code and provides services that make the development process easier. This runtime environment in .NET Framework is known as Common Language Runtime (CLR). The CLR sits at the very heart of managed code. Common Language Runtime is the generalized multi-language, reflective execution engine on which code originally written in various languages runs. At a higher level, CLR is simply an engine that takes in Intermediate Language (IL) instructions, translates them into machine instructions, and xecutes them. Although the common language runtime provides many standard runtime services, managed code is never interpreted. A feature calledjust-in-time (JIT) compiling enables all managed code to run in the native machine language of the system on which it is executing. The CLR shares much in common with a traditional operating system.

Quote:
Managed code is the term used for any code that is running on .NET Framework.

The CLR provides the infrastructure that enables managed code to execute as well provides variety of services during execution. When a method, for which IL has been generated, is called for the first time the CLR compiles the IL into native code that is specific totheprocessortheEnvironment it is running on (This process is known as Just in Time Compilation or JIT). If the same method is called next time, the existing JIT compiled code is reused. During execution managed code receives variety of services from the runtime environment.

Quote:
When compiling to managed code, the compiler translates your source code into Microsoft intermediate language (MSIL), which is a CPU-independent set of instructions that can be efficiently converted to native code. Intermediate Language is a binary assembly language that is compiled at runtime down to whatever machine language is appropriate for the host CPU. This runtime compilation is called Just-In-Time Compiling or JIT-compiling.

Advantages of Managed Execution Environments
In unmanaged environments the compiler and linker directly compile the source code in to native instructions that are targeted at a specific processor. The disadvantage of this process is that each time you want to run your executable on a different platform you will have to re-compile the code using a compiler and linker that will compile the code that is targeted at the specific hardware. This means that each time you want your application to run on a different platform, you will have to ship the compiled instructions again and again. As this leads to compiling and maintaining multiple versions of the same application, the companies try to create a more generalized compiled version in order to target most of the environments. This process is known as the Lowest Common Denominator approach. This leads to a more generalized program which is not optimized properly and does not take advantages of the underlying hardware infrastructure (processor, cache, etc). Because the CLR supplies one or more Just in Time Compiler for each computer architecture it supports, the same set of MSIL can be JIT-compiled and run on any supported architecture.
This CLR provides the following benefits for developers:
Vastly simplified development.
Seamless integration of code written in various languages.
Evidence-based security with code identity.
Assembly-based deployment that eliminates DLL Hell.
Side-by-side versioning of reusable components.
Code reuse through implementation inheritance.
Automatic object lifetime management.
Code access security.
Cross Language Integration.
Self describing objects.

The CLR automatically handles object layout and manages references to objects, releasing them when they are no longer being used. This automatic memory management resolves the two most common application errors, memory leaks and invalid memory references. This process is known as Garbage Collection. The CLR also manages thread execution, code execution, code safety verification, compilation, and other system services.
The CLR is designed for the software of the future, and it also supports software of today and yesterday. Interoperability between managed and unmanaged code provided by CLR helps developers continue to use necessary COM components and DLLs.
What is Delegate and what is it used for ?
Delegate is kinda like a pointer to a function in C++ or like an event handler in Java
You can use it to “multicast” which means running multiple functions in different instances of object already created.
This is useful when you want your objects to “register” to an event raised by another object.
The way it works is the object you are registered to listen to recieves the delegate of the function it is supposed to run in your object, the delegate is then run from it. (if you switch the word delegate for pointer, this would be much simpler)How is meant by DLL ?
A DLL (Dynamic Link Library) is a file that can be loaded and executed by programs dynamically. Basically it’s an external code repository for programs. Since usually several different programs reuse the same DLL instead of having that code in their own file, this dramatically reduces required storage space. A synonym for a DLL would be library.Which DLL translate XML to SQL in IIS?
Sqlisapi.dll
Can anyone tell me about Secure Socket Layer? How to make use of the technology?
Secure Sockets Layer (SSL) and Transport Layer Security (TLS), its successor, are cryptographic protocols which provide secure communications on the Internet. There are slight differences between SSL 3.0 and TLS 1.0, but the protocol remains substantially the same. The term “SSL” as used here applies to both protocols unless clarified by context.What is the Differnce Between Response.write & response.output.Write
In ASP.NET the Response object is of type HttpResponse and when you say Response.Write you’re really saying (basically) HttpContext.Current.Response.Write and calling one of the many overloaded Write methods of HttpResponse.
Response.Write then calls .Write() on it’s internal TextWriter object:
public void Write(object obj){ this._writer.Write(obj);}
HttpResponse also has a Property called Output that is of type, yes, TextWriter, so:
public TextWriter get_Output(){ return this._writer; }
Which means you can to the Response whatever a TextWriter will let you. Now, TextWriters support a Write() method ala String.Format, so you can do this:
Response.Output.Write(”Scott is {0} at {1:d}”, “cool”,DateTime.Now);
But internally, of course, this this is happening:
public virtual void Write(string format, params object[] arg)
{
this.Write(string.Format(format, arg));
}Which dll is required to translate XML to SQL in IIS ?
Microsoft.data.sqlxml.dll

What is an interface and what is an abstract class? Please, expand by examples of using both. Explain why.
Answers1:
In a interface class, all methods are abstract without implementation where as in an abstract class some methods we can define concrete. In interface, no accessibility modifiers are allowed. An abstract class may have accessibility modifiers. Interface and abstract class are basically a set of rules which u have to follow in case u r using them(inheriting them).

Answers2:
Abstract classes are closely related to interfaces. They are classes that cannot be instantiated, and are frequently either partially implemented, or not at all implemented. One key difference between abstract classes and interfaces is that a class may implement an unlimited number of interfaces, but may inherit from only one abstract (or any other kind of) class. A class that is derived from an abstract class may still implement interfaces. Abstract classes are useful when creating components because they allow you specify an invariant level of functionality in some methods, but leave the implementation of other methods until a specific implementation of that class is needed. They also version well, because if additional functionality is needed in derived classes, it can be added to the base class without breaking code.

Answers3:
Abstract Classes
An abstract class is the one that is not used to create objects. An abstract class is designed to act as a base class (to be inherited by other classes). Abstract class is a design concept in program development and provides a base upon which other classes are built. Abstract classes are similar to interfaces. After declaring an abstract class, it cannot be instantiated on it’s own, it must be inherited. Like interfaces, abstract classes can specify members that must be implemented in inheriting classes. Unlike interfaces, a class can inherit only one abstract class. Abstract classes can only specify members that should be implemented by all inheriting classes.

Answers4:
An interface looks like a class, but has no implementation. They’re great for putting together plug-n-play like architectures where components can be interchanged at will. Think Firefox Plug-in extension implementation. If you need to change your design, make it an interface. However, you may have abstract classes that provide some default behavior. Abstract classes are excellent candidates inside of application frameworks.

Answers5:
One additional key difference between interfaces and abstract classes (possibly the most important one) is that multiple interfaces can be implemented by a class, but only one abstract class can be inherited by any single class.
Some background on this: C++ supports multiple inheritance, but C# does not. Multiple inheritance in C++ has always be controversial, because the resolution of multiple inherited implementations of the same method from different base classes is hard to control and anticipate. C# decided to avoid this problem by allowing a class to implement multiple interfaces, which do not contain method implementations, but restricting a class to have at most a single parent class. Although this can result in redundant implementations of the same method when different classes implement the same interface, it is still an excellent compromise.
Another difference between interfaces and abstract classes is that an interface can be implemented by an abstract class, but no class, abstract or otherwise, can be inherited by an interface.

Answers6:
What is an Abstract class?
An abstract class is a special kind of class that cannot be instantiated. So the question is why we need a class that cannot be instantiated? An abstract class is only to be sub-classed (inherited from). In other words, it only allows other classes to inherit from it but cannot be instantiated. The advantage is that it enforces certain hierarchies for all the subclasses. In simple words, it is a kind of contract that forces all the subclasses to carry on the same hierarchies or standards.
What is an Interface?
An interface is not a class. It is an entity that is defined by the word Interface. An interface has no implementation; it only has the signature or in other words, just the definition of the methods without the body. As one of the similarities to Abstract class, it is a contract that is used to define hierarchies for all subclasses or it defines specific set of methods and their arguments. The main difference between them is that a class can implement more than one interface but can only inherit from one abstract class. Since C# doesn’t support multiple inheritance, interfaces are used to implement multiple inheritance.What is serialization, how it works in .NET?
Serialization is when you persist the state of an object to a storage medium so an exact copy can be re-created at a later stage.
Serialization is used to save session state in ASP.NET.
Serialization is to copy objects to the Clipboard in Windows Forms
Serialization is used by remoting to pass objects by value from one application domain to another
What should one do to make class serializable?
Answers1:
To make a class serializable is to mark it with the Serializable attribute as follows.
[Serializable]
public class MyObject {
public int n1 = 0;
public int n2 = 0;
public String str = null;
}
What exactly is being serialized when you perform serialization?
The object’s state (values)How does output caching work in ASP.NET?
Output caching is a powerful technique that increases request/response throughput by caching the content generated from dynamic pages. Output caching is enabled by default, but output from any given response is not cached unless explicit action is taken to make the response cacheable.

To make a response eligible for output caching, it must have a valid expiration/validation policy and public cache visibility. This can be done using either the low-level OutputCache API or the high-level @ OutputCache directive. When output caching is enabled, an output cache entry is created on the first GET request to the page. Subsequent GET or HEAD requests are served from the output cache entry until the cached request expires.
The output cache also supports variations of cached GET or POST name/value pairs.
The output cache respects the expiration and validation policies for pages. If a page is in the output cache and has been marked with an expiration policy that indicates that the page expires 60 minutes from the time it is cached, the page is removed from the output cache after 60 minutes. If another request is received after that time, the page code is executed and the page can be cached again. This type of expiration policy is called absolute expiration – a page is valid until a certain time.

What is connection pooling and how do you make your application use it?
Opening database connection is a time consuming operation.
Connection pooling increases the performance of the applications by reusing the active database connections instead of create new connection for every request.
Connection pooling Behaviour is controlled by the connection string parameters.
Follwing the the 4 parameters that control most of the connection pooling behaviour.
1. Connect Timeout
2. Max Pool Size
3. Min Pool Size
4. Pooling

What are different methods of session maintenance in ASP.NET?
3 types:
In-process storage.
Session State Service.
Microsoft SQL Server.

In-Process Storage
The default location for session state storage is in the ASP.NET process itself.

Session State Service
As an alternative to using in-process storage for session state, ASP.NET provides the ASP.NET State Service. The State Service gives you an out-of-process alternative for storing session state that is not tied quite so closely to ASP. Net’s own process.

To use the State Service, you need to edit the sessionState element in your ASP.NET application’s web.config file:
You’ll also need to start the ASP.NET State Service on the computer that you specified in the stateConnectionString attribute. The .NET Framework installs this service, but by default it’s set to manual startup. If you’re going to depend on it for storing session state, you’ll want to change that to automatic startup by using the Services MMC plug-in in the Administrative Tools group.

If you make these changes, and then repeat the previous set of steps, you’ll see slightly different behavior: session state persists even if you recycle the ASP.NET process.

There are two main advantages to using the State Service. First, it is not running in the same process as ASP.NET, so a crash of ASP.NET will not destroy session information. Second, the stateConnectionString that’s used to locate the State Service includes the TCP/IP address of the service, which need not be running on the same computer as ASP.NET. This allows you to share state information across a web garden (multiple processors on the same computer) or even across a web farm (multiple servers running the application). With the default in-process storage, you can’t share state information between multiple instances of your application.

The major disadvantage of using the State Service is that it’s an external process, rather than part of ASP.NET. That means that reading and writing session state is slower than it would be if you kept the state in-process. And, of course, it’s one more process that you need to manage. As an example of the extra effort that this can entail, there is a bug in the initial release of the State Service that allows a determined attacker to crash the ASP.NET process remotely. If you’re using the State Service to store session state, you should install the patch from Microsoft Security Bulletin MS02-66, or install SP2 for the .NET Framework.

Microsoft SQL Server
The final choice for storing state information is to save it in a Microsoft SQL Server database. To use SQL Server for storing session state, you need to perform several setup steps:

Run the InstallSqlState.sql script on the Microsoft SQL Server where you intend to store session state. This script will create the necessary database and database objects. The .NET Framework installs this script in the same folder as its compilers and other tools–for example, C:\WINNT\Microsoft.NET\Framework\v1.0.3705 on a Windows 2000 computer with the 1.0 version of the Framework. Edit the sessionState element in the web.config file for your ASP.NET application as follows:

Supply the server name, user name, and password for a SQL Server account that has access to the session state database in the sqlConnectionString attribute.
Like the State Service, SQL Server lets you share session state among the processors in a web garden or the servers in a web farm. But you also get the additional benefit of persistent storage. Even if the computer hosting SQL Server crashes and is restarted, the session state information will still be present in the database, and will be available as soon as the database is running again. That’s because SQL Server, being an industrial-strength database, is designed to log its operations and protect your data at (almost) all costs. If you’re willing to invest in SQL Server clustering, you can keep the session state data available transparently to ASP.NET even if the primary SQL Server computer crashes.

Like the State Service, SQL Server is slower than keeping session state in process. You also need to pay additional licensing fees to use SQL Server for session state in a production application. And, of course, you need to worry about SQL Server-specific threats such as the “Slammer” worm.

What is Viewstate?
A server control’s view state is the accumulation of all its property values. In order to preserve these values across HTTP requests, ASP.NET server controls use this property, which is an instance of the StateBag class, to store the property values.

Can any object be stored in a Viewstate?
An object that either is serializable or has a TypeConverter defined for it can be persisted in ViewState

What should you do to store an object in a Viewstate?
Do serialization of convert the object to string

Explain how Viewstate is being formed and how it’s stored on client.
The type of ViewState is System.Web.UI.StateBag, which is a dictionary that stores name/value pairs. ViewState is persisted to a string variable by the ASP.NET page framework and sent to the client and back as a hidden variable. Upon postback, the page framework parses the input string from the hidden variable and populates the ViewState property of each control. If a control uses ViewState for property data instead of a private field, that property automatically will be persisted across round trips to the client. (If a property is not persisted in ViewState, it is good practice to return its default value on postback.)

What do you know about ADO.NET’s objects and methods?
ADO.NET provides consistent access to data sources such as Microsoft SQL Server, as well as data sources exposed through OLE DB and XML.
Data-sharing consumer applications can use ADO.NET to connect to these different data sources and retrieve, manipulate, and update data.
ADO.NET provides first-class support for the disconnected, n-tier programming environment for which many new applications are written.

Explain DataSet.AcceptChanges and DataAdapter.Update methods.
DataAdapter.Update method Calls the respective INSERT, UPDATE, or DELETE statements for each inserted, updated, or deleted row in the DataSet.
DataSet.AcceptChanges method Commits all the changes made to this row since the last time AcceptChanges was called.

When we go for html server controls and when we go for web server controls?
Server controls are a part of ASP.net. When a server control is used there will be an extra overhead on the server to create the control at runtime and accordingly set the values. HTML controls are static controls and are easy to use. They are supported is ASP.net.
As a rule, if there is a corresponding HTML control available instead of the server control, you should always go for the HTML control as it enhances the server performance and ensures faster response. Server controls should be used when it is found that the available HTML controls are not sufficient to achieve the task.

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Practice paper

Filed under: plcement paper — colwmk @ 9:30 pm

1.find perimeter of a trapezium wit 3 sides given and distance b/w parallel sides given…

2.a triangle ABC is given, a line DE is parallel to base side and that cuts the triangle.. the ratio of area of triangle to the area of trapezium .given DE/BC=3/5..

3.four concentric circles r given .the radius of 1st circle is x.next is 2x,then 3x and 4x. given that area b/w 2nd and 1st is A and 4th and 3rd circles being B.find ratio of A to B

4.difference b/w the perimeters of two concentric circles is 66.find the difference b/w radius..
Ans: 10.5

5.3/p=6,3/q=15……find p-q

Quantitative were simple mostly geometrical type…. technical questions…..……

1.which of de following is connectionless protocol
Ans: UDP

2. #define clrscr() 100
main()
{
clrscr();
printf(“%d”,clrscr());
}

3. which of the followin is used for avoidin network congestion
bufferin
cachin
sourcequench
all of de above

4.main()
{
int a;
printf(“%d”,scanf(%d,&a));
}

what’s o/p of this program. what will b printed
Ans :0

5. main()
{
printf(“as”);
printf(“\bhi”);
printf(“is\n”);
}
what will b printed.

6.main()
{
unsigned short a=-1;
unsigned char b=a;

printf(“%d %d “,a,b);
}

what is o/p of the program

a. 65535 -1
b. 65535 65535
c. -1 -1

7.arrays base address is 1000….array is a[5][4]..then what is The correct address of a[4][3]…
Ans:1056

8.one packet is 64bytes..no of pkts send is 16000..then total no of bytes send is

Ans: 1024000

9.#define maxval 5
int main (void)
{
int i=1;
if(i-maxval)
{
printf(“inside”);
}
else
{
printf(“out”);
}
find o/p???

10. #define a 3+3
#define b 11-3
main()

{
printf(“%d”,a*b);
}
what is o/p?????

11.a question in which segment address is given ..logical address is 800..base addresses also given ..u hav 2 find physical address..

12.stack is used in a task
Ans: temporary variables values

13.which of de following is not stored in activation record..
Ans: some heap area

14.main{
printf(“%d”,-1<<4);

}

what’s o/p???

Ans: 0xfff0

15.main()
{
int* s
s=10
printf(“%d,%d,%d,%d,%d,%d”,*s++,(*s)++,++*s,++(*s));

}
what’s o/p???

16.there was a question on processor speed in nanocycles..then it performs a instruction in x cycles..dont remember

17. main()

{
int *i;

int s=(int *)malloc(10*sizeof(int));
for (i=0;i<10;i++)
{
printf(“%d”,i*i)
}
what’s o/p

18. one more similar question

COMPUTER AWARENESS TEST

1.In the command scanf, h is used for

Ans. Short int

2.A process is defined as

Ans. Program in execution

3.A thread is

Ans. Detachable unit of executable code)

4.What is the advantage of Win NT over Win 95

Ans. Robust and secure

5.How is memory management done in Win95

Ans. Through paging and segmentation

6.What is meant by polymorphism

Ans. Redfinition of a base class method in a derived class

7.What is the essential feature of inheritance

Ans. All properties of existing class are derived

8.What does the protocol FTP do

Ans. Transfer a file b/w stations with user authentification

9.In the transport layer ,TCP is what type of protocol

Ans. Connection oriented

10.Why is a gateway used

Ans. To connect incompatible networks

11.How is linked list implemented

Ans. By referential structures

12.What method is used in Win95 in multitasking

Ans. Non preemptive check

13.What is meant by functional dependency

14.What is a semaphore

Ans. A method synchronization of multiple processes

15.What is the precedence order from high to low ,of the symbols ( ) ++ /

Ans.( ) , ++, /

16.Preorder of A*(B+C)/D-G

Ans.*+ABC/-DG

18. B-tree (failure nodes at same level)

19. Dense index (index record appers for every search -key in file)

20.What is the efficiency of merge sort

Ans. O(n log n)

21.A program on swaping ( 10,5 )was given (candidate cannot recollect)

22.In which layer are routers used

Ans.In network layer

23.In which layer are packets formed ( in network layer )

24.heap ( priority queue )

25.copy constructor ( constant reference )

26.Which of the following sorting algorithem has average sorting behavior –Bubble sort,merge sort,heap sort,exchange sort

Ans. Heap sort

27.In binary search tree which traversal is used for getting ascending order values–Inorder ,post order,preorder

Ans. Inorder

28.What are device drivers used for

Ans. To provide software for enabling the hardware

29. Irrevalent to unix command ( getty)

30.What is fork command in unix?

Ans. System call used to create process

31.What is make command in unix?

Ans. Used forcreation of more than one file

32.In unix .profile contains

Ans. Start up program

33.In unix echo is used for ?

Ans. C

34.In unix ‘ls ’stores contents in

Ans.inode block

QUANTITATIVE SECTION

1.In a class composed of x girls and y boys what part of the class is composed of girls

A. y/(x + y) B. x/xy C. x/(x + y) D. y/xy
Ans. C

2.What is the maximum number of half-pint bottles of cream that can be filled with a 4-gallon can of cream(2 pt.=1 qt. and 4 qt.=1 gal)

A.16 B.24 C.30 D.64

Ans.D

3.If the operation,^ is defined by the equation x ^ y = 2x + y,what is the value of a in 2 ^ a = a ^ 3

A.0 B.1 C.-1 D.4

Ans.B

4.A coffee shop blends 2 kinds of coffee, putting in 2 parts of a 33p. a gm. grade to 1 part of a 24p. a gm.If the mixture is changed to 1 part of the 33p. a gm. to 2 parts of the less expensive grade,how much will the shop save in blending 100 gms.

A.Rs.90 B.Rs.1.00`C.Rs.3.00 D.Rs.8.00

Ans. C

5.There are 200 questions on a 3 hr examination.Among these questions are 50 mathematics problems.It is suggested that twice as much time be spent on each maths problem as for each other question.How many minutes should be spent on mathematics problems

A.36 B.72 C.60 D.100

Ans. B

6.In a group of 15,7 have studied Latin, 8 have studied Greek, and 3 have not studied either.How many of these studied both Latin and Greek

A.0 B.3 C.4 D.5

Ans. B

7.If 13 = 13w/(1-w) ,then (2w)2 =

A.1/4 B.1/2 C.1 D.2

Ans. C

8. If a and b are positive integers and (a-b)/3.5 = 4/7, then

(A) b < a (B) b > a (C) b = a (D) b >= a

Ans. A

9. In June a baseball team that played 60 games had won 30% of its game played. After a phenomenal winning streak this team raised its average to 50% .How many games must the team have won in a row to attain this average?

A. 12 B. 20 C. 24 D. 30

Ans. C

10. M men agree to purchase a gift for Rs. D. If three men drop out how much more will each have to contribute towards the purchase of the gift/

A. D/(M-3) B. MD/3 C. M/(D-3) D. 3D/(M2-3M)

Ans. D

11. A company contracts to paint 3 houses. Mr.Brown can paint a house in 6 days while Mr.Black would take 8 days and Mr.Blue 12 days. After 8 days Mr.Brown goes on vacation and Mr. Black begins to work for a period of 6 days. How many days will it take Mr.Blue to complete the contract?

A. 7 B. 8 C. 11 D. 12

Ans. C

12. 2 hours after a freight train leaves Delhi a passenger train leaves the same station travelling in the same direction at an average speed of 16 km/hr. After traveling 4 hrs the passenger train overtakes the freight train. The average speed of the freight train was?

A. 30 B. 40 C.58 D. 60

Ans. B

13. If 9x-3y=12 and 3x-5y=7 then 6x-2y = ?

A.-5 B. 4 C. 2 D. 8

Ans. D

ANALYTICAL ABILITY

1. The office staff of XYZ corporation presently consists of three bookkeepers–A, B, C and 5 secretaries D, E, F, G, H. The management is planning to open a new office in another city using 2 bookkeepers and 3 secretaries of the present staff . To do so they plan to separate certain individuals who don’t function well together. The following guidelines were established to set up the new office

I. Bookeepers A and C are constantly finding fault with one another and should not be sent together to the new office as a team
II. C and E function well alone but not as a team , they should be separated
III. D and G have not been on speaking terms and shouldn’t go together
IV Since D and F have been competing for promotion they shouldn’t be a team

1.If A is to be moved as one of the bookkeepers, which of the following cannot be a possible working unit.

A.ABDEH B.ABDGH C.ABEFH D.ABEGH

Ans.B

2.If C and F are moved to the new office, how many combinations are possible

A.1 B.2 C.3 D.4

Ans. A

3.If C is sent to the new office, which member of the staff cannot go with C

A. B B. D C. F D. G

Ans. B

4.Under the guidelines developed, which of the following must go to the new office

A. B B. D C .E D. G

Ans. A

5.If D goes to the new office, which of the following is/are true

I. C cannot go II. A cannot go III. H must also go

A. I only B. II only C. I and II only D. I and III only

Ans. D

2.After months of talent searching for an administrative assistant to the president of the college the field of applicants has been narrowed down to 5–A, B, C, D, E .It was announced that the finalist would be chosen after a series of all-day group personal interviews were held.The examining committee agreed upon the following procedure

I. The interviews will be held once a week
II.3 candidates will appear at any all-day interview session
III. Each candidate will appear at least once
IV. If it becomes necessary to call applicants for additional interviews, no more 1 such applicant should be asked to appear the next week
V. Because of a detail in the written applications, it was agreed that whenever candidate B appears, A should also be present.
VI. Because of travel difficulties it was agreed that C will appear for only 1 interview.

1.At the first interview the following candidates appear A,B,D.Which of the follwing combinations can be called for the interview to be held next week.

A. BCD B. CDE C. ABE D. ABC

Ans. B

2.Which of the following is a possible sequence of combinations for interviews in 2 successive weeks

A. ABC;BDE B. ABD;ABE C. ADE;ABC D. BDE;ACD

Ans. C

3.If A ,B and D appear for the interview and D is called for additional interview the following week,which 2 candidates may be asked to appear with D?

I. A II B III. C IV. E

A. I and II B. I and III only C. II and III only D.III and IV only

Ans. D

4.Which of the following correctly state’s) the procedure followed by the search committee

I. After the second interview all applicants have appeared at least once
II. The committee sees each applicant a second time b If a third session, it is possible for all applicants to appear at least twice

A. I only B. II only C. III only D. Both I and II

Ans. A

3. A certain city is served by subway lines A,B and C and numbers 1 2 and 3 When it snows , morning service on B is delayed
When it rains or snows , service on A, 2 and 3 are delayed both in the morning and afternoon When temp. falls below 30 degrees farenheit afternoon service is cancelled in either the A line or the 3 line, but not both. When the temperature rises over 90 degrees farenheit, the afternoon service is cancelled in either the line C or the 3 line but not both. When the service on the A line is delayed or cancelled, service on the C line which connects the A line, is delayed. When service on the 3 line is cancelled, service on the B line which connects the 3 line is delayed.

Q1. On Jan 10th, with the temperature at 15 degree farenheit, it snows all day. On how many lines will service be
affected, including both morning and afternoon.

(A) 2 (B) 3 (C) 4 (D) 5

Ans. D

Q2. On Aug 15th with the temperature at 97 degrees farenheit it begins to rain at 1 PM. What is the minimum number
of lines on which service will be affected?

(A) 2 (B) 3 (C) 4 (D) 5

Ans. C

Q3. On which of the following occasions would service be on the greatest number of lines disrupted.

(A) A snowy afternoon with the temperature at 45 degree farenheit
(B) A snowy morning with the temperature at 45 degree farenheit
(C) A rainy afternoon with the temperature at 45 degree farenheit
(D) A rainy afternoon with the temperature at 95 degree farenheit

Ans. B

4. In a certain society, there are two marriage groups, red and brown. No marriage is permitted within a group. On marriage, males become part of their wives groups; women remain in their own group. Children belong to the same group as their parents. Widowers and divorced males revert to the group of their birth. Marriage to more than one person at the same time and marriage to a direct descendant are forbidden

Q1. A brown female could have had

I. A grandfather born Red II. A grandmother born Red III Two grandfathers born Brown

(A) I only (B) III only (C) I, II and III (D) I and II only

Ans. D

Q2. A male born into the brown group may have

(A) An uncle in either group (B) A brown daughter (C) A brown son (D) A son-in-law born into red group

Ans. A

Q3. Which of the following is not permitted under the rules as stated.

(A) A brown male marrying his father’s sister (B) A red female marrying her mother’s brother
(C) A widower marrying his wife’s sister (D) A widow marrying her divorced daughter’s ex-husband

Ans. B

Q4. If widowers and divorced males retained their group they had upon marrying which of the following would be permissible ( Assume that no previous marriage occurred)

(A) A woman marrying her dead sister’s husband (B) A woman marrying her divorced daughter’s ex-husband
(C) A widower marrying his brother’s daughter (D) A woman marrying her mother’s brother who is a widower.

Ans. D

5. I. All G’s are H’s II. All G’s are J’s or K’s III All J’s and K’s are G’s
IV. All L’s are K’s V. All N’s are M’s VI. No M’s are G’s

Q1. If no P’s are K’s which of the following must be true

(A) No P is a G (B) No P is an H (C) If any P is an H it is a G (D) If any P is a G it is a J

Ans. D

Q2. Which of the following can be logically deduced from the stated conditions

(A) No M’s are H’s (B) No H’s are M’s (C) Some M’s are H’s (D) No N’s are G’s

Ans. D

Q3. Which of the following is inconsistent with one or more conditions

(A) All H’s are G’s (B) All H’s are M’s (C) Some H’s are both M’s and G’s (D) No M’s are H’s

Ans. C

Q4. The statement “No L’s are J’s” is

I. Logically deducible from the conditions stated
II Consistent with but not deducible from the conditions stated
III. Deducible from the stated conditions together with the additional statements “No J’s are K’s”

(A) I only (B) II only (C) III only (D) II and III only

Ans. D

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Computer Architecture

Filed under: plcement paper — colwmk @ 9:28 pm

Microsoft Placement Paper (Computer Architecture)

Computer Architecture

1. Explain what is DMA?
2. What is pipelining?
3. What are superscalar machines and vliw machines?
4. What is cache?
5. What is cache coherency and how is it eliminated?
6. What is write back and write through caches?
7. What are different pipelining hazards and how are they eliminated.
8. What are different stages of a pipe?
9. Explain more about branch prediction in controlling the control hazards
10. Give examples of data hazards with pseudo codes.
11. How do you calculate the number of sets given its way and size in a cache?
12. How is a block found in a cache?
13. Scoreboard analysis.
14. What is miss penalty and give your own ideas to eliminate it.
15. How do you improve the cache performance.
16. Different addressing modes.
17. Computer arithmetic with two’s complements.
18. About hardware and software interrupts.
19. What is bus contention and how do you eliminate it.
20. What is aliasing?
21) What is the difference between a latch and a flip flop?
22) What is the race around condition? How can it be overcome?
23) What is the purpose of cache? How is it used?
24) What are the types of memory management?

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Algo and programming

Filed under: plcement paper — colwmk @ 9:28 pm

Algorithms and Programming

1. Given a rectangular (cuboidal for the puritans) cake with a rectangular piece removed (any size or orientation), how would you cut the remainder of the cake into two equal halves with one straight cut of a knife ?

2. You’re given an array containing both positive and negative integers and required to find the sub-array with the largest sum (O(N) a la KBL). Write a routine in C for the above.

3. Given an array of size N in which every number is between 1 and N, determine if there are any duplicates in it. You are allowed to destroy the array if you like. [ I ended up giving about 4 or 5 different solutions for this, each supposedly better than the others ].

4. Write a routine to draw a circle (x ** 2 + y ** 2 = r ** 2) without making use of any floating point computations at all. [ This one had me stuck for quite some time and I first gave a solution that did have floating point computations ].

5. Given only putchar (no sprintf, itoa, etc.) write a routine putlong that prints out an unsigned long in decimal. [ I gave the obvious solution of taking % 10 and / 10, which gives us the decimal value in reverse order. This requires an array since we need to print it out in the correct order. The interviewer wasn't too pleased and asked me to give a solution which didn't need the array ].

6. Give a one-line C expression to test whether a number is a power of 2. [No loops allowed - it's a simple test.]

7. Given an array of characters which form a sentence of words, give an efficient algorithm to reverse the order of the words (not characters) in it.

8. How many points are there on the globe where by walking one mile south, one mile east and one mile north you reach the place where you started.

9. Give a very good method to count the number of ones in a “n” (e.g. 32) bit number.

ANS. Given below are simple solutions, find a solution that does it in log (n) steps.

Iterative
function iterativecount (unsigned int n)
begin
int count=0;
while (n)
begin
count += n & 0×1 ;
n >>= 1;
end
return count;
end
Sparse Count
function sparsecount (unsigned int n)
begin
int count=0;
while (n)
begin
count++;
n &= (n-1);
end
return count ;
end

10. What are the different ways to implement a condition where the value of x can be either a 0 or a 1. Apparently the if then else solution has a jump when written out in assembly. if (x == 0) y=a else y=b There is a logical, arithmetic and a data structure solution to the above problem.

11. Reverse a linked list.

12. Insert in a sorted list

13. In a X’s and 0’s game (i.e. TIC TAC TOE) if you write a program for this give a fast way to generate the moves by the computer. I mean this should be the fastest way possible.

The answer is that you need to store all possible configurations of the board and the move that is associated with that. Then it boils down to just accessing the right element and getting the corresponding move for it. Do some analysis and do some more optimization in storage since otherwise it becomes infeasible to get the required storage in a DOS machine.

14. I was given two lines of assembly code which found the absolute value of a number stored in two’s complement form. I had to recognize what the code was doing. Pretty simple if you know some assembly and some fundaes on number representation.

15. Give a fast way to multiply a number by 7.

16. How would go about finding out where to find a book in a library. (You don’t know how exactly the books are organized beforehand).

17. Linked list manipulation.

18. Tradeoff between time spent in testing a product and getting into the market first.

19. What to test for given that there isn’t enough time to test everything you want to.

20. First some definitions for this problem: a) An ASCII character is one byte long and the most significant bit in the byte is always ‘0′. b) A Kanji character is two bytes long. The only characteristic of a Kanji character is that in its first byte the most significant bit is ‘1′.

Now you are given an array of a characters (both ASCII and Kanji) and, an index into the array. The index points to the start of some character. Now you need to write a function to do a backspace (i.e. delete the character before the given index).

21. Delete an element from a doubly linked list.

22. Write a function to find the depth of a binary tree.

23. Given two strings S1 and S2. Delete from S2 all those characters which occur in S1 also and finally create a clean S2 with the relevant characters deleted.

24. Assuming that locks are the only reason due to which deadlocks can occur in a system. What would be a foolproof method of avoiding deadlocks in the system.

25. Reverse a linked list.

Ans: Possible answers -

iterative loop
curr->next = prev;
prev = curr;
curr = next;
next = curr->next
endloop

recursive reverse(ptr)
if (ptr->next == NULL)
return ptr;
temp = reverse(ptr->next);
temp->next = ptr;
return ptr;
end

26. Write a small lexical analyzer – interviewer gave tokens. expressions like “a*b” etc.

27. Besides communication cost, what is the other source of inefficiency in RPC? (answer : context switches, excessive buffer copying). How can you optimize the communication? (ans : communicate through shared memory on same machine, bypassing the kernel _ A Univ. of Wash. thesis)

28. Write a routine that prints out a 2-D array in spiral order!

29. How is the readers-writers problem solved? – using semaphores/ada .. etc.

30. Ways of optimizing symbol table storage in compilers.

31. A walk-through through the symbol table functions, lookup() implementation etc. – The interviewer was on the Microsoft C team.

32. A version of the “There are three persons X Y Z, one of which always lies”.. etc..

33. There are 3 ants at 3 corners of a triangle, they randomly start moving towards another corner.. what is the probability that they don’t collide.

34. Write an efficient algorithm and C code to shuffle a pack of cards.. this one was a feedback process until we came up with one with no extra storage.

35. The if (x == 0) y = 0 etc..

36. Some more bitwise optimization at assembly level

37. Some general questions on Lex, Yacc etc.

38. Given an array t[100] which contains numbers between 1..99. Return the duplicated value. Try both O(n) and O(n-square).

39. Given an array of characters. How would you reverse it. ? How would you reverse it without using indexing in the array.

40. Given a sequence of characters. How will you convert the lower case characters to upper case characters. ( Try using bit vector – solutions given in the C lib -typec.h)

41. Fundamentals of RPC.

42. Given a linked list which is sorted. How will u insert in sorted way.

43. Given a linked list How will you reverse it.

44. Give a good data structure for having n queues ( n not fixed) in a finite memory segment. You can have some data-structure separate for each queue. Try to use at least 90% of the memory space.

45. Do a breadth first traversal of a tree.

46. Write code for reversing a linked list.

47. Write, efficient code for extracting unique elements from a sorted list of array. e.g. (1, 1, 3, 3, 3, 5, 5, 5, 9, 9, 9, 9) -> (1, 3, 5, 9).

48. Given an array of integers, find the contiguous sub-array with the largest sum.

ANS. Can be done in O(n) time and O(1) extra space. Scan array from 1 to n. Remember the best sub-array seen so far and the best sub-array ending in i.

49. Given an array of length N containing integers between 1 and N, determine if it contains any duplicates.

ANS. [Is there an O(n) time solution that uses only O(1) extra space and does not destroy the original array?]

50. Sort an array of size n containing integers between 1 and K, given a temporary scratch integer array of size K.

ANS. Compute cumulative counts of integers in the auxiliary array. Now scan the original array, rotating cycles! [Can someone word this more nicely?]

* 51. An array of size k contains integers between 1 and n. You are given an additional scratch array of size n. Compress the original array by removing duplicates in it. What if k << n?

ANS. Can be done in O(k) time i.e. without initializing the auxiliary array!

52. An array of integers. The sum of the array is known not to overflow an integer. Compute the sum. What if we know that integers are in 2’s complement form?

ANS. If numbers are in 2’s complement, an ordinary looking loop like for(i=total=0;i< n;total+=array[i++]); will do. No need to check for overflows!

53. An array of characters. Reverse the order of words in it.

ANS. Write a routine to reverse a character array. Now call it for the given array and for each word in it.

* 54. An array of integers of size n. Generate a random permutation of the array, given a function rand_n() that returns an integer between 1 and n, both inclusive, with equal probability. What is the expected time of your algorithm?

ANS. “Expected time” should ring a bell. To compute a random permutation, use the standard algorithm of scanning array from n downto 1, swapping i-th element with a uniformly random element <= i-th. To compute a uniformly random integer between 1 and k (k < n), call rand_n() repeatedly until it returns a value in the desired range.

55. An array of pointers to (very long) strings. Find pointers to the (lexicographically) smallest and largest strings.

ANS. Scan array in pairs. Remember largest-so-far and smallest-so-far. Compare the larger of the two strings in the current pair with largest-so-far to update it. And the smaller of the current pair with the smallest-so-far to update it. For a total of <= 3n/2 strcmp() calls. That’s also the lower bound.

56. Write a program to remove duplicates from a sorted array.

ANS. int remove_duplicates(int * p, int size)
{
int current, insert = 1;
for (current=1; current < size; current++)
if (p[current] != p[insert-1])
{
p[insert] = p[current];
current++;
insert++;
} else
current++;

return insert;

}

57. C++ ( what is virtual function ? what happens if an error occurs in constructor or destructor. Discussion on error handling, templates, unique features of C++. What is different in C++, ( compare with unix).

58. Given a list of numbers ( fixed list) Now given any other list, how can you efficiently find out if there is any element in the second list that is an element of the first list (fixed list).

59. Given 3 lines of assembly code : find it is doing. IT was to find absolute value.

60. If you are on a boat and you throw out a suitcase, Will the level of water increase.

61. Print an integer using only putchar. Try doing it without using extra storage.

62. Write C code for (a) deleting an element from a linked list (b) traversing a linked list

63. What are various problems unique to distributed databases

64. Declare a void pointer ANS. void *ptr;

65. Make the pointer aligned to a 4 byte boundary in a efficient manner ANS. Assign the pointer to a long number and the number with 11…1100 add 4 to the number

66. What is a far pointer (in DOS)

67. What is a balanced tree

68. Given a linked list with the following property node2 is left child of node1, if node2 < node1 else, it is the right child.

O P
|
|
O A
|
|
O B
|
|
O C

How do you convert the above linked list to the form without disturbing the property. Write C code for that.

O P
|
|
O B
/ \
/ \
/ \
O ? O ?

determine where do A and C go

69. Describe the file system layout in the UNIX OS

ANS. describe boot block, super block, inodes and data layout

70. In UNIX, are the files allocated contiguous blocks of data

ANS. no, they might be fragmented

How is the fragmented data kept track of

ANS. Describe the direct blocks and indirect blocks in UNIX file system

71. Write an efficient C code for ‘tr’ program. ‘tr’ has two command line arguments. They both are strings of same length. tr reads an input file, replaces each character in the first string with the corresponding character in the second string. eg. ‘tr abc xyz’ replaces all ‘a’s by ‘x’s, ‘b’s by ‘y’s and so on. ANS.
a) have an array of length 26.
put ‘x’ in array element corr to ‘a’
put ‘y’ in array element corr to ‘b’
put ‘z’ in array element corr to ‘c’
put ‘d’ in array element corr to ‘d’
put ‘e’ in array element corr to ‘e’
and so on.

the code
while (!eof)
{
c = getc();
putc(array[c - 'a']);
}

72. what is disk interleaving

73. why is disk interleaving adopted

74. given a new disk, how do you determine which interleaving is the best a) give 1000 read operations with each kind of interleaving determine the best interleaving from the statistics

75. draw the graph with performance on one axis and ‘n’ on another, where ‘n’ in the ‘n’ in n-way disk interleaving. (a tricky question, should be answered carefully)

76. I was a c++ code and was asked to find out the bug in that. The bug was that he declared an object locally in a function and tried to return the pointer to that object. Since the object is local to the function, it no more exists after returning from the function. The pointer, therefore, is invalid outside.

77. A real life problem – A square picture is cut into 16 squares and they are shuffled. Write a program to rearrange the 16 squares to get the original big square.

78.
int *a;
char *c;
*(a) = 20;
*c = *a;
printf(“%c”,*c);

what is the output?

79. Write a program to find whether a given m/c is big-endian or little-endian!

80. What is a volatile variable?

81. What is the scope of a static function in C ?

82. What is the difference between “malloc” and “calloc”?

83. struct n { int data; struct n* next}node;
node *c,*t;
c->data = 10;
t->next = null;
*c = *t;
what is the effect of the last statement?

84. If you’re familiar with the ? operator x ? y : z
you want to implement that in a function: int cond(int x, int y, int z); using only ~, !, ^, &, +, |, <<, >> no if statements, or loops or anything else, just those operators, and the function should correctly return y or z based on the value of x. You may use constants, but only 8 bit constants. You can cast all you want. You’re not supposed to use extra variables, but in the end, it won’t really matter, using vars just makes things cleaner. You should be able to reduce your solution to a single line in the end though that requires no extra vars.

85. You have an abstract computer, so just forget everything you know about computers, this one only does what I’m about to tell you it does. You can use as many variables as you need, there are no negative numbers, all numbers are integers. You do not know the size of the integers, they could be infinitely large, so you can’t count on truncating at any point. There are NO comparisons allowed, no if statements or anything like that. There are only four operations you can do on a variable.
1) You can set a variable to 0.
2) You can set a variable = another variable.
3) You can increment a variable (only by 1), and it’s a post increment.
4) You can loop. So, if you were to say loop(v1) and v1 = 10, your loop would execute 10 times, but the value in v1 wouldn’t change so the first line in the loop can change value of v1 without changing the number of times you loop.
You need to do 3 things.
1) Write a function that decrements by 1.
2) Write a function that subtracts one variable from another.
3) Write a function that divides one variable by another.
4) See if you can implement all 3 using at most 4 variables. Meaning, you’re not making function calls now, you’re making macros. And at most you can have 4 variables. The restriction really only applies to divide, the other 2 are easy to do with 4 vars or less. Division on the other hand is dependent on the other 2 functions, so, if subtract requires 3 variables, then divide only has 1 variable left unchanged after a call to subtract. Basically, just make your function calls to decrement and subtract so you pass your vars in by reference, and you can’t declare any new variables in a function, what you pass in is all it gets.
Linked lists

* 86. Under what circumstances can one delete an element from a singly linked list in constant time?

ANS. If the list is circular and there are no references to the nodes in the list from anywhere else! Just copy the contents of the next node and delete the next node. If the list is not circular, we can delete any but the last node using this idea. In that case, mark the last node as dummy!

* 87. Given a singly linked list, determine whether it contains a loop or not.

ANS. (a) Start reversing the list. If you reach the head, gotcha! there is a loop!
But this changes the list. So, reverse the list again.
(b) Maintain two pointers, initially pointing to the head. Advance one of them one node at a time. And the other one, two nodes at a time. If the latter overtakes the former at any time, there is a loop!

p1 = p2 = head;
do {
p1 = p1->next;
p2 = p2->next->next;
} while (p1 != p2);

88. Given a singly linked list, print out its contents in reverse order. Can you do it without using any extra space?

ANS. Start reversing the list. Do this again, printing the contents.

89. Given a binary tree with nodes, print out the values in pre-order/in-order/post-order without using any extra space.

90. Reverse a singly linked list recursively. The function prototype is node * reverse (node *) ;

ANS.

node * reverse (node * n)
{
node * m ;
if (! (n && n -> next))
return n ;

m = reverse (n -> next) ;
n -> next -> next = n ;
n -> next = NULL ;
return m ;
}

91. Given a singly linked list, find the middle of the list.

HINT. Use the single and double pointer jumping. Maintain two pointers, initially pointing to the head. Advance one of them one node at a time. And the other one, two nodes at a time. When the double reaches the end, the single is in the middle. This is not asymptotically faster but seems to take less steps than going through the list twice.

Bit-manipulation

92. Reverse the bits of an unsigned integer.

ANS.

* 93. Compute the number of ones in an unsigned integer.

ANS.

#define count_ones(x) \
(x=(0xaaaaaaaa&x)>>1+(0×55555555&x), \
x=(0xcccccccc&x)>>2+(0×33333333&x), \
x=(0xf0f0f0f0&x)>>4+(0×0f0f0f0f&x), \
x=(0xff00ff00&x)>>8+(0×00ff00ff&x), \
x=x>>16+(0×0000ffff&x))

94. Compute the discrete log of an unsigned integer.

ANS.

#define discrete_log(h) \
(h=(h>>1)|(h>>2), \
h|=(h>>2), \
h|=(h>>4), \
h|=(h>>8), \
h|=(h>>16), \
h=(0xaaaaaaaa&h)>>1+(0×55555555&h), \
h=(0xcccccccc&h)>>2+(0×33333333&h), \
h=(0xf0f0f0f0&h)>>4+(0×0f0f0f0f&h), \
h=(0xff00ff00&h)>>8+(0×00ff00ff&h), \
h=(h>>16)+(0×0000ffff&h))

If I understand it right, log2(2) =1, log2(3)=1, log2(4)=2….. But this macro does not work out log2(0) which does not exist! How do you think it should be handled?

* 95. How do we test most simply if an unsigned integer is a power of two?

ANS. #define power_of_two(x) \ ((x)&&(~(x&(x-1))))

96. Set the highest significant bit of an unsigned integer to zero.

ANS. (from Denis Zabavchik) Set the highest significant bit of an unsigned integer to zero
#define zero_most_significant(h) \
(h&=(h>>1)|(h>>2), \
h|=(h>>2), \
h|=(h>>4), \
h|=(h>>8), \
h|=(h>>16))

97. Let f(k) = y where k is the y-th number in the increasing sequence of non-negative integers with the same number of ones in its binary representation as y, e.g. f(0) = 1, f(1) = 1, f(2) = 2, f(3) = 1, f(4) = 3, f(5) = 2, f(6) = 3 and so on. Given k >= 0, compute f(k).

Others

98. A character set has 1 and 2 byte characters. One byte characters have 0 as the first bit. You just keep accumulating the characters in a buffer. Suppose at some point the user types a backspace, how can you remove the character efficiently. (Note: You cant store the last character typed because the user can type in arbitrarily many backspaces)

99. What is the simples way to check if the sum of two unsigned integers has resulted in an overflow.

100. How do you represent an n-ary tree? Write a program to print the nodes of such a tree in breadth first order.

101. Write the ‘tr’ program of UNIX. Invoked as

tr -str1 -str2. It reads stdin and prints it out to stdout, replacing every occurance of str1[i] with str2[i].

e.g. tr -abc -xyz
to be and not to be <- input
to ye xnd not to ye <- output

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Algo and programming

Filed under: plcement paper — colwmk @ 9:25 pm

Algorithms and Programming

1. Given a rectangular (cuboidal for the puritans) cake with a rectangular piece removed (any size or orientation), how would you cut the remainder of the cake into two equal halves with one straight cut of a knife ?