Mr. Snjeev Kumar  is working as an Academic Consultant in the School of Computer and Information Sciences (SOCIS) of Indira Ghandhi National Open University (IGNOU), New Delhi. He writes weekly technical columns based on IT and computer and also writes career related article in national newspaper like Hindustan, Amar Ujala for last 4-5 years as an IT expert. He has participated in various conferences.

 

Also, He is one of esteemed Expert Career Guide at MeraCareerGuide.com.

You can read Sanjeev Kumar’s recent article in Amar Ujala- on his weekly column "Digital Corner"

 

Headline: Cyber Security

 

Published Date: Wednesday, 19th October, 2011

   

 

Click here to read :  Cyber Security- Safe Career in Virtual World

 

In the series of technical interview question, this is my fourth post. Here i am posting very basic questions related with .NET concept. Following  questions are kind of introductory and usually asked in any .NET interview.  

Que1:What are access specifiers?
Ans: Access specifiers are provided by .NET to achieve security of object and its member. It is important if you are doing some object oriented work.

Que2: What are the access specifiers provided by .NET?
Ans: There are five access specifiers in c#:
public : The type or member can be accessed by any code in the same assembly or another assembly that references it.
private : The type or member cannot be accessed outside the class.
protected : The type or member are accessible within the class or struct and the class derived (Inherited )from this class.
internal : The type or member are accessible within same assembly level.
protected internal :  The type or member can be accessed anywhere in the same assembly and in the derived class.

Que3: What is XMLHTTPRequest object?
Ans: XMLHttpRequest is an API available in web browser scripting language to make Ajax calls. It sends HTTP or HTTPS requests to web server and load server response.

Que4: XMLHTTPRequest is a browser property or a part of HTML DOM?
Ans: It is browser property.

Que5: What are generics?
Ans: Generics is a way provided by .NET(Or JAVA) to define a classes or methods(or Interface) that can have placeholders (type parameters) for one or more of the types. In simple words Generics are the way to define any logic without worrying about the type. At run time it can take the type and can apply the logic on it(Of course some compile time check will be there by compiler).

Que6: Why Generics?
Ans: There are few advantages of having Generics.
a) Type safety: There is compile time checking done,which prevents developer to caste wrong type,and prevents run time exception.
Ex:
int i = 5;
Object o = i;
String str = (String)o;
Code written above causes problem at run time.
b) performance:Without generics i.e. with object class we need a lot of boxing/unboxing, causing performance degradation.
c) Source code protection: Developers don't need any source code if they are using generic algorithms.

Que7: What are LINQ?
Ans: LINQ: Language Integrated query. It is similar to database query but you can use it in .net to filter the desired data from any (IEnumerable)collection.

Que8: What are advantages of having LINQ?
Ans: LINQ is very much declarative,so it is easier to write and understand. The protection and optimization provided by framework is also a big advantage.

Que9: What is AppDomain?
Ans: AppDomain is logical container for set of assemblies.It is kind of shell to make application secure. In .NET Dll get loaded inside AppDomain of corresponding application. It can also be interpreted as isolation of memory used by application.

Que10: What is difference between AppDomain and a process?
Ans: The purpose of both AppDomain and process is to provide security but at different level. A process is Operating System level concept whereas AppDomain is .NET level concept.  An AppDomain can belong to only one process, but a process can have more than one AppDomain in it.

Please go through the questions. The answers given are a little short and doesn't give the detail explaination. The topics covered here are very important, and i will suggest you to explore them in detail.

In the series of technical interview question, this is my second post. Here i am posting very basic questions related with .NET concept. Following  questions are usually asked in any .NET interview.  

Que1: What is serialization/Deserialization?

Ans: Serialization is the process of converting an object into a stream of bytes. Deserialization is the opposite process of creating an object from a stream of bytes. Serialization/Deserialization is mostly used to transport objects.

Que2: What are the ways available in .NET Framework to support serialization?

Ans: There are two separate mechanisms provided by the .NET class library - XmlSerializer and SoapFormatter/BinaryFormatter.

Que3: How can i customise the serialization process?

Ans: XmlSerializer supports attributes like xmlIgnore and xmlElement, that can be used to configure serialization. For example,by [XmlIgnore] attribute, we can exclude field/property from serialization and by [XmlElement] attribute we can specify element name to be used for a perticular field.

Que4: How can we serialize a Hashtable?

Ans: XmlSerializer will refuse to serialize instances of any class that implements IDictionary. So we need to customize our serialization process with attributes like xmlIgnore and xmlElement. We can pass array of Key value pair type object and on the other side can deserialize into Hashtable again.

Que5: What is CAS?

Ans: Code access security (CAS) is a feature provided by the CLR. Code access security is the part of the .NET security model that determines whether or not a piece of code is allowed to run, and what resources it can use when it is running.

Que6: What is Boxing and unboxing ?

Ans: Boxing: The conversion of a value type instance to an object.
        Un-Boxing: The conversion of an object instance to a value type.

Que7: What is difference between const and readonly?

Ans: const are evaluated at compile time, wherease readonly are eveluated at run time. const need to be initialized at declaration,but readonly can be declared once and can be assigned in the code also. const can not be static, but readonly can be static as well as instance-level.

Que8: What is delegate?

Ans: Delegate is reference to a method. It is similar to function pointer in c++.

Que9: What are events?

Ans: Events are ways of notification. When something interesting happens and we want to execute any function on that thing, we can associate events with that.Events are declared using delegates only.

Que10: What is advantage of for loop over foreach loop?

Ans: We can modify collection by adding new value while traversing on it by for loop, but in foreach, if we add any new value in collection, it will throw an exception. foreach loop  requires collection to be enumerable,such constrant is not there in for loop.

Please go through the questions. The answers given are a little short and doesn't give the detail explaination. The topics covered here are very important, and i will suggest you to explore them in detail.

In the series of technical interview question, this is my second post. Here i am posting very basic questions related with .NET concept. Following  questions are usually asked in any .NET interview.  

1) What is the CLR?

CLR = Common Language Runtime. It is runtime environment provided which has standard resources that any .NET program can take advantage of,regardless of programming language. CLR runtime manages memory,thread execution, code safety verification, compilation and other system services.

2) What is the CTS?

CTS = Common Type System. This is the range of types that the .NET runtime understands, and therefore that .NET applications can use. Not all .NET languages will support all the types in the CTS. The CTS is a superset of the CLS.

3) What is the CLS?

CLS = Common Language Specification. All .NET languages supports CLS. The idea is that any program which uses CLS-compliant types can interoperate with any .NET program written in any language.

4)What is an Assembly?

An Assembly is a  logical unit of code.Assembly physically exist as DLLs or EXEs. Every assembly file contains information about itself. This information is called as Assembly Manifest.

5) What is IL?

IL = Intermediate Language. Also known as MSIL (Microsoft Intermediate Language) or CIL (Common Intermediate Language). .Net code of any language gives IL after compilation. The IL is then converted to machine code at the point where the software is installed, or at run-time by a Just-In-Time (JIT) compiler.

6) What is managed code?

Code that has its execution managed by CLR. It is the responsibility of framework to provide memory management, security etc.The necessary information is encoded in intermediate language and associated metadata.

7) What is difference between DLL and EXE?

Dll is class library but an exe is executable. Code having main() method is kept inside EXE but other supporting files are kept inside DLLs.

8)What is COM?

COM:Component Object Model.It is method by which different application  of different language can talk with each other. It is interoperability standard.

9)What is GC (Garbage Collection)?

GC is one of the feature provided by CLR which runs in the background collecting unused object references.Developer need not to necessarily destroy and free the memory manually.

10)What is Reference type and value type ?

Reference Type:

Reference type are those datatype which contains address of memory where actual data is stored. Reference types are allocated on the managed CLR heap. The value of a reference type is the location of the sequence of bits that represent the type's data.

Value Type:

Value types are type which keeps value within their own memory location.Value types are allocated on the stack just like primitive types. Value types are not instantiated using new, and out of scope when the function they are defined within returns.

Please go through these questions and i will suggest you to go into detail of every key word i mentioned, from different resources available on net.

Inorder to help students do well in interviews I decided to upload few technical questions from field of IT. In coming days I will post various common Java, C amd .Net related questions which if learnt will get you succesfully through interview. So, here are few questions with their answers.   

Que1: What is difference between Process and Thread?
Ans: Process and threads are methods to get parallel execution of an application. A process have its own address space, where multiple thread can execute, It means a process can have multiple threads in it. Multiple process can interact with each others only by Inter process communication mechanism thus Inter process communication is always expensive but inter thread communication is cheap. As two process uses separate memory spaces thus if one process dies it never affects other process, but if one thread gets corrupt then other thread(and sometimes corresponding process) will get die.

Que2: What are abstract classes?
Ans: Class that contains one or more methods which are only declared not defined.In other words Abstract class is class which have one or more abstract methods(Method without body). We can not have any object of abstract class.But it can be sub classed, and that subclass have to implement all abstract methods else this subclass too have to declare as abstract class. Abstract class can be used to refer an object reference, so that at run time we can decide which method of subclass to execute.

Que3: What is an interface?
Ans: Interface is an abstract class with all abstract methods. Interface is generally defined to show a contract that any class implementing this interface will implement methods in it.
Note: Syntax for both abstract class and interface is different. The definition given it only for understanding.

Que4: What is the difference abstract class and interface?
Ans: In Abstract class contains one or many abstract methods but an interface have only abstract methods. A class can be a subclass of only one abstract class, but a class can implement one or many interfaces. Interface is a way to achieve multiple inheritance.

Que5: What is overriding?
Ans: When method name and its  parameters (signature) are same in sub and super class but its definition is different. it is called as overriding.

Que6: What is overloading?
Ans: Method with same name and different signature in same class, is called method overloading.

Que7: What are different ways to block a thread in Java?
Ans: There are 3 ways:
    Sleep(): thread will be blocked for specific amount of time.
    Suspend(): thread need to use resume() to return back.
    wait(): thread need to use notify() to return back.

Que8: What is JAR file?
Ans: JAR file is a kind of zip file for Java application containing application or libraries in the form of classes and associated meta data and resources.

Que9: What is the difference between "==" and .equals() method?
Ans: "==" compares object reference only but .equals compares its fields. Generally to compare any 2 objects use .equals method not "==".

Que10: What is the difference between constructor and methods?
Ans: Constructor has same name as class name, no other method can have name as class name. Constructor has no return type, not even void. constructor may or may not be explicitly defined for any class, Java does provide a default constructor.