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Oracle interview questions and answers

oracle-squarelogoThese are the technical interviews questions which are asked to the student who is attending an interview on the oracle platform. Clearing the technical round of an interview is not an easy task and the candidate must have a very good knowledge on all the concepts. These are the interview questions collected from various interview and kept at one place and made convenient to the students. This article helps in the preparation process before facing technical interview on oracle platform.

  1. Define oracle table?

The basic unit of storing data in the oracle database is known as a table. All the tables in the daatabase hold data which is accessible by user. The table can be stored rows and columns.

  1. Define clusters?

One or more group of tables physically store to share columns and are mainly used together is known as clusters.

  1. Define an index?

The optional structure which is related to a table to have direct access to rows is an index. To increase the performance of data retrieval, index is created. Index is created on many columns of a table.

  1. Give the advantages of views?
  • Ensure additional level of security to the table by limiting the access to predetermined set of columns and rows in a table.
  • Data complexity is hidden.
  • The user commands are simplified.
  • Data is presented in different perspective from the base table.
  • Complex queries are stored.
  1. Mention different types of queries?
  • Sub queries
  • Normal queries
  • Nested queries
  • Co-related queries
  • Compound queries
  1. Differentiate clustered and non-clustered index?

A cluster index is a special index in which way of records in the table is reordered is stored physically. Thus, there is only one clustered index to the table. Data pages are present in the leaf nodes of the clustered index. In non-clustered index, the index’s logical order does not match physical stored order of rows on the disk.

  1. Define null value?

Null value is not a blank space or zero. The unknown value that occupies four bytes in the SQL memory is known as null value.

  1. What is a transaction?

Transaction is defined as a sequence of SQL statements that are treated by the oracle database as a single unit.

  1. Differentiate SQL and oracle?

SQL is nothing but a Structured Query Language where are oracle is a database. The queries against oracle database are written using SQL.

  1. Give different database objects of oracle?
  • Views
  • Tables
  • TableSpaces
  • Sequences
  • Synonyms
  • Indexes
  1. Define schema?

The collection of database objects of the user is known as a schema.

  1. Define roles?

The named groups of associated privileges granted to roles or other users.

  1. Define hash cluster?

The hash cluster which is stored in a row based on result of applying hash function to the cluster key value of the row. The rows which have same hash key value can be stored together in the disk.

  1. Define a SNAPSHOT?

The master table’s read-only copies located on remote node which is refreshed occasionally to reflect changes performed on the master table.

  1. Define database instance?

The set of background processes and memory structure that gain access to set of database files are known as a database instance. The processes are shared among all the users.

  1. What are different types of joins?
  • Self join
  • Cartesian join
  • Outer join
  • Equi joins
  1. How many triggers are applied to a single table?

12 triggers

  1. Which command is used to create backup constrol file?

To trace, the database backup control file is altered.

  1. Give different configurations of a table?

One of the following configurations must be there in a table:

  • A clustered index
  • No indexes
  • A non-clustered index
  • Clustered and non-clustered indexes
  • Many non-clustered indexes
  1. Differentiate between UNIQUE and PRIMARY KEY constraint?

Null values can be present in the column which is defined as UNIQUE but not in PRIMARY KEY. There is only one primary key for a table.

  1. Define BCP and when it is used?

The tool which is used to copy excess data from views and tables is known as BulkCopy. The structures same as source to destination are not copied using BCP.

  1. Define integrity constraint?

In a relational database, consistency and accuracy are ensured using integrity constraints.

  1. Differentiate explicit and implicit cursors?

Automatically, an implicit cursor is created for the user by oracle when the query is executed. It is easy to code.

An explicit cursor is created by you. It takes more code but ensures good control and ignore if there are DBA_DATA_FILES.

  1. Define primary key?

Each row in a table is identified uniquely using primary key. There is only one primary key to the table.

  1. What is default return value of function?

Integer is the default return value of a function.

  1. Define oracle, SQL and SQL server?

Oracle is based on relational database management system whereas SQL is a structured query language and it is the other tool for RDMS which is provided by Microsoft.

  1. Define data segments?

The physical areas in the database block in which data related with clusters and tables are stored is known as data segment.

  1. Why SAVEPOINTS are used?

A transaction is subdivided into smaller parts using SAVEPOINTS. The rolling back part of the transaction is enabled using SAVEPOINTS. At most five save points are permitted.

Ajax interview questions and answers

download (2)The students who are looking for interview questions and answers on Ajax is at the right place because this article has the best interview questions. These are the frequently asked interview questions in most of the interviews. All these questions are given appropriate and simple answers so that the students feel easy to remember. This article helps in the preparation process and the candidate does well in the interview.


  1. Define Ajax?

The full form of Ajax is asynchronous JavaScript and XML. It is not the latest technology but an old technology represented in new way. It avid unstable control that auto post back on the server side every time. It is a time consuming technology.

  1. Give the object used for AJAX request?

XmlHttpRequest object.

  1. Differentiate Ajax request and normal request to the server?

With Ajax a postback from client goes partially to the server that is a partial post back is triggered instead of complete postback using XmlHttpRequest object.

  1. Give the browsers supporting XmlHttpRequest object?
  • Mozilla 1.0+/Firefox
  • Opera 8.0+
  • Internet Explorer 5.0+
  • Safari 1.2+
  1. Can Ajax is implemented in the browsers which are not supporting XmlHttpRequest object?

Yes. Here, remote scripts can be used.

  1. Give different types of Ready States in Ajax?
  • Request sent
  • Request not initialized
  • Request completed
  • Request processing
  • Request set
  1. How Ajax is used in ASP.NET 2.0?

For ASP.NET 2.0, ASP.NET Ajax framework 1.0 is available as an individual download.

  1. Give the different controls in ASP.NET Ajax Framework 1.0?
  • Update progress
  • Update panel
  • Script Manager Proxy
  • Script Manager
  • Timer
  1. For Update Panel use, what is the prerequisite?

Script Manager

    10. How many update panels can we have in one page?

As many as required

  1. Does Ajax work along with Java?

Absolutely, Java is the perfect fit for Ajax. To generate Ajax client pages manage server side state of Ajax clients, serve incoming requests of Ajax and clients of Ajax are connected to the enterprise resources, using Java Enterprise Edition servers. To define and use Ajax components, the perfect fit is JavaServer Faces component model.

  1. What does Ajax component frameworks provides?

The following are some of the features that are provided by Ajax component frameworks:

  • Skinning facilities
  • Programmatic control
  • Customization Applications
  • Extensibility

The functions mentioned above are bit slower in their execution.

  1. Describe about direct Ajax frameworks?

If you are interested in using Ajax frameworks directly then it is necessary to have a HTML, CSS and Ajax enterprise. Authoring must be done in HTML and Ajax framework deals directly with HTML. Ajax offers several APIs and frameworks for different purposes such as DOM, event handling, COM and the elements that are rich in graphics are altered. These frameworks can be used for shopping frameworks but this framework is not recommended for web-based applications.

  1. Explain multimedia functions of Ajax?

In general, there is no build-in multimedia function in Ajax but it makes use of other plug-ins and functionalities like Quicktime, SVG and flash plug-in. Multimedia can be achieved in Ajax using hack and mashup. Excellent application can be build using multimedia functions. These multimedia applications can also be obtained from outside.

  1. Describe the friendliness of Ajax with SEO?

Ajax is the combination of multiple languages such as CSS, JavaScript, etc. Ajax is not friendly with search engine indexing as much of the code is written using JavaScript. In general, search engines will not use the index JavaScript which is present in the web pages.

  1. Explain why HTTP POST request is used by Ajax?

If you are interested in verifying whether an email address is used or not using Ajax as URL does not support character @ directly in email address. Thus, HTTP POST is used for this purpose.

  1. Are there any frameworks help in speedup development using Ajax?

Multiple browser-side frameworks are available and each has own uniqueness.

  1. Are applications developed using AJAX are easy than traditional web applications?

Certainly, Ajax applications run complex JavaScript code on the client. It is not an easy task to make the complex code bug free and efficient and to meet the challenges, better development frameworks and tools are used.

  1. How the Ajax code is tested?

For the client-side JavaScript, a port of JUnit known as JsUnit is used to test the Ajax code.

  1. Define W3C DOM?

It is a platform-and language neutral interface.

  1. Does the code written in Ajax cross compatibility of the browser?

Not completely. Many browsers provide a native XMLHttpRequest JavaScript object whereas other (internet explorer) requires you to get as active object.

  1. Is Ajax is an architectural style or technology platform?

Ajax is both. A set of technologies that are used in specific way is known as Ajax.

Python interview questions and answers

learn-python-programmingThe interview questions presented in this article are collected from various interview papers conducted by many multinational companies. It is the right place to get the appropriate information on Python interview questions and answers. The students who are attending an interview on the platform of python can effectively make use of this article while preparing for an interview. Clearing the technical round of an interview require hard work and commitment of the student. The student must revise all the major concepts of the language quickly by going through this article.

1. Define python?
Python language is simple and it is very easy to learn this language when compared to other programming languages. Python language is dynamic object oriented language which is used for developing software. It supports various programming languages and has massive library support for many different languages.

2. In python language, define a method?
A function on object x is a method which is called as…). Inside the definition of class, methods are defined as functions:
class C:
def meth(self, atg):
return arg*2+self.attribute

3. Define self?
Simply, self is a conventional name for the method’s first argument. A method which is defined as meth(self, x ,y ,z) is called as a.meth(x, y, z) for an instance of a class in which definition occurs and the called think it is called as meth(a, x ,y, z).

4. Describe python usage in web programming?
Python is perfectly used for web programming and has special features to make it easy programming language. Web frame works, content management systems, WebServers, CGI scripts, Webclient programming, Webservices, etc are the features supported by python. Python language is used to create various high end applications because of its flexibility.

5. Is there any tool used to find bugs or carrying out static analysis?
Yes. The static analysis tool which is used to find bugs in the source code of python and warns about code style and complexity is known as PyChecker. Pylint is a tool that verifies whether a module satisfies standards of coding and makes it possible to add custom feature and write plug-ins.
6. In python, give the rules for local and global variables?
In python, the variables referenced inside a function are global. When a variable is assigned new value anywhere in the body of a function then it is assumed as local. In a function, if a variable ever assigned new value then the variable is implicitly local and explicitly it should be declared as global. If all global references require global then you will be using global at anytime. You’d declare as global each reference to built-in function or to component of module which is imported. The usefulness of global declaration in identifying side-effects is defeated by this clutter.

7. How to find methods or attributes of an object?
dir(x) returns a list of names in the alphabetical order which contains instant attributes and methods defined by the class for instance x of user-defined class.

8. Is there any equivalent to scanf() or sscanf()?
Usually, the easy way to divide line into whitespace-delimited words for simple input parsing use split() method of string objects. Then, decimal strings are converted to numeric values using float() or int(). An optional “sep” parameter is supported by split() which is useful if something is used in the place of whitespace as separator. For complex input parsing, regular expressions are powerful then sscanf() of C and perfectly suits for the task.

9. Define class?
A class is a specific object type which is created when the class statement is executed. To create instances objects, class objects can be used as templates which represent both code and data specific to datatype.
In general, a class is based on one or many classes known as base classes. It inherits methods and attributes of base classes. An object model is now permitted to redefine successively using inheritance. Basic accessor methods are provided by generic Mailbox for subclasses and mailbox like MaildirMailbox, MboxMailbox, OutlookMailbox which handle many specific formats of mailbox.

10. How to prevent blocking in content() method of socket?
Commonly, select module is used to help asynchronous I/O.
11. In python, are there any databases to DB packages?
Bsddb package is present in Python 2.3 which offers an interface to BerkeleyDatabase library. It Interface to hashes based on disk such as GDBM and DBM are included in standard python.

12. How random numbers are generated in python?
Random number generator is implemented by standard random module.

PHP interview Questions


Hyper text preprocessor is a scripting language of computer which is especially designed for creating dynamic web pages. The syntax of specific languages such as Perl, Java, C and PHP are embedded in HTML pages for execution on the server side it has command line interface capability and it is effectively used in the independent graphical applications. It is deployed on many web servers and on every operating system. In general, PHP is installed on more than 1million web services and 25 million websites. In this article, you will find the interview questions on PHP along with the best possible answers. These are the more frequently asked interview questions by the employers in the interview. This article is helpful for the candidate who is attending an interview on PHP platform in the IT industry.

  1. What is PHP?

PHP hyper text preprocessor is a simple programming language which is used by the developers to build dynamic content to interact with databases. Mainly, PHP is used to create software applications which are based on the web.

  1. Who is father of PHP?

The father of PHP is Rasmus Lerdorf.

  1. Define Session?

A logical object which is developed by the PHP engine that allows you to maintain data across successive HTTP requests is known as a session. At any time, only one session object is available to the PHP scripts. Data preserved to session by the script is retrieved by the same or other script when it is requested from same visitor. Commonly, temporary data are stored using sessions thereby allowing several PHP pages to provide complete functional transaction for same visitor.

  1. In PHP, what is PEAR?

The next revolution is a PHP is PEAR. A higher level programming is brought to PHP by this repository. For reusable PHP components, PEAR is considered as an effective framework and distribution system. Installation is eased by bringing automated wizard and combining PHP user’s strength and experience into finely organized OOP library. A command-line interface is also offered by PEAR that is used to install packages automatically.

  1. Define persistent cookie?

The cookie which is stored in the cookie file permanently on browser’s system is known as persistent cookie. Basically, cookies are developed as temporary cookies which can be stored in the memory of the browser’s. The created temporary cookies are removed if the browser is closed. You must know when to use persistent cookies and temporary cookies according to their differences:

  • Long-term information cannot be tracked by using temporary cookies.
  • Long-term information can be effectively tracked using persistent cookies.
  • Temporary programs are highly safe and secure because no other program can access them except browser.
  • There is less security for persistent cookies because cookies files can be opened by the users to see cookie values.
  1. Describe different errors in PHP?

In PHP, there are three basic types of runtime errors, they are:


These are serious errors. Example: attempting to include () file which is not available. These errors are showed to the user by default but they will not result in ending the script.


These errors are non-critical and trivial errors that come across while executing the script in PHP. Example: trying to gain access the variable which is not defined. These errors are not showed to the users by default even if the default behavior is changed.

Fatal errors:

These are critical errors. Example: instantiating an object of a class which does not exist or a non-existent function is called. These errors results in termination of the script immediately and default behavior of PHP is shown to them when they take place. Twelve different error types are used to represent these variations internally.

  1. How a cookie is destroyed?

The cookie is set with past expiration time.

  1. Describe features and benefits of object oriented programming?

The major advantage of object oriented programming is ease of modification. Modification and adding of objects is easy thereby reducing the maintenance cost. Modeling the real world is better using object oriented programming than procedure-oriented programming. More complicated and flexible interactions are possible by it. Non-technical personnel can also feel comfortable working with OO programming and they take part in enhancement and maintenance of system as it influences natural human cognition patterns. For few systems, the development time is made speed by object oriented approach as many objects are standard across systems and are reused. Purchasing the components that manage shopping, shipping, dates, etc is easy and are used for modifying particular system.

  1. Differentiate require and include?

Both require and include are used for including a file but if the included file is not found then a warning is sent by include whereas a fatal error is sent by require.

  1. In PHP, header () function is used for what?

A raw HTTP header is sent by the header () function to the client. Redirection of pages can be done using header () function. Make sure to notice that before seeing the actual output a header () function must be called.

  1. How PHP script is executed using command line?

You must run command line interface program of PHP and file name of PHP script is given as the command line argument.

  1. Differentiate GET and POST methods?

In general, there are some differences between GET and POST methods:

  • In GET method, you may have some restrictions like 2kb data should be send for request whereas you can send unlimited data using POST method.
  • When a GET method is requested data is shown in URL but not in POST method. Thus, POST method is considered as the best method for sending sensitive request.


  1. Differentiate procedure oriented and object oriented languages?

In general, there is much difference between procedure oriented and object oriented languages:

  • A new developer feels procedure oriented is easy but understanding whole software is complex when compared to object oriented model.
  • It is very difficult to use design patterns such as singleton pattern, MVC etc in procedure oriented language whereas in object oriented programming language it is very easy to develop design patterns.
  • In OOP languages the code can be reused using polymorphism and inheritance but it is not possible in procedure oriented language.
  1. In PHP, what type of inheritance is supported?

Extended class depends on single base class in PHP that is Multiple Inheritance is not supported by PHP. “Extends” is the keyword which is sued to extend class.

  1. Differentiate primary and unique key?

Primary key:

The values of a column in a table identify uniquely rows of the table. The value of primary key cannot be NULL.

Unique key:

Each row is uniquely identified using unique keys in the table. Every unique key value must have only one row. NULL is also a unique key. In general, you may have many unique keys and only one primary key for a table.

  1. Describe garbage collection?

The automated part of PHP is garbage collection, the objects which are not used in the program for longer time is removed or eliminated or deleted by the garbage collector. The process of garbage collection runs in default session saves directory that is /tmp. The garbage collector will ignores it, when your sessions are saved in a different directory. The process of garbage collection does not differentiate the sessions belong to whom when it is in the running stage. It is a vital note on the shared web services. The files that are not gained access in the directory are deleted by the garbage collector when the process runs.

These technical interview questions and answers discussed in the above session are the frequently asked questions by most of the multinational companies in their interviews. This article is helpful in the preparation process of an interview.

Java interview questions

In this article, you will find interview questions and answers on Java. These interview qdi-logo-java-orangeuestions and answers are asked by the employers in the technical round of an interview. These questions are useful for the candidate who is attending an interview in the software industry on the Java platform. The interview questions presented in this article are collected from various Java interviews conducted by the multinational companies. These interview questions on Java are consolidated in one place to make it easy and convenient for you. This article helps in the preparation process of Java technical interview.

 1. What is the vital feature in Java?

The main feature in Java language is platform independent.

2. What is platform independent?

The Java code which is written and compiled in one platform such as windows can execute class in the other platforms such as Linux, UNIX, etc is known as platform independent.

3. Define JVM?

JVM- java Virtual Machine
For compiled java class files, JVM is considered as a runtime environment.

4. Differentiate JDK and JVM?

JDK – Java Development Kit
JVM – Java Virtual Machine
It is used for development which has an execution environment whereas JVM is runtime environment purely and thus, the source files cannot be compiled using JVM.

5. Define a pointer and does Java language support pointers?

In general, pointer is a reference to memory location. Reliability issues and memory leaks are possible by handling pointers improperly. Thus, usage of Java is not supported by Java.
6. Differentiate abstract class and interface?
Instance methods which are used for building default behavior are present in an abstract class. In an interface, you can declare only instance methods and constants but the default behavior cannot be built and implicitly all the methods are abstract. All the public methods without implementation are present in an interface. In an abstract class, you can declare the class members as protected, private, etc but, it has few abstract methods.

7. Define static in java?
The meaning of static is one for each class and not for every object and the existence of instance of a class is not considered. So, you can use without creating instance for that particular class. The methods which are declared as static are final implicitly as overriding is done depending on type of object. In general, methods declared as static can be attached to a class but not an object. Static method in a super class is shadowed by other static method in subclass until the actual method is not declared as final. But, it is not possible to override a static method using a non-static method. Simply in a subclass, a static method cannot be changed to an instance method.

8. In Java, what is the use of garbage collector?
Garbage collection is used to spot and remove objects that are not used by the program from long time and the allocate resources for that object is reclaimed and reused. The memory allocated by the Java object is deleted if it is unreachable within the same program.

9. Explain synchronization with respect to multi-threading?
The ability to control access to shared resources of multiple threads with respect to multithreading is known as synchronization. One thread can modify shared variable whereas other thread is in the process of updating or using the same shared variable, without synchronization. Usually, this may lead to different errors.

10. Describe the ways of using thread?
Runnable interface is used to implement a thread or you can also inherit from a Thread class. Formal is beneficial as if you are going for multiple inheritance then only an interface is helpful.
11. Differentiate method and a constructor?
A member function of a class which is used for creating objects for that particular class is known as a constructor. The constructor name and class name is same. A constructor does not have a return type and new operator is used to invoke a constructor. An ordinary member function of a class is known as a method. A method has a return type and own name but dot operator is used to invoke it.

12. Define an Iterator?
Some collection classes offer their contents traversal through an interface called java.util.Iterator. You can walk through the collection of objects using this interface, in turn operates on every object. While traversing an iterator, it is not suggested to modify collection.

13. Define pass by reference?
In pass by reference, address itself is passed instead of passing the value.

14. Define pass by value?
In pass by value, a copy of value is passed.

15. Define Map and HashMap?
A Map is an interface whereas Hash Map is class implementing that.
16. Define Vector and ArrayList?
Vector is synchronized but Array List is not synchronized.

17. Define Swing and Awt?
Swings are light weight components whereas AWT are heavy weight components. Thus, Swings works fast when compared to AWT.

18. Define final?
If a class is declared using final keyword then it cannot be extended. i.e., final class will not have a subclass. A method declared with final keyword cannot be overridden if its class is inherited. It is not possible to change the value of a final variable.

19. Define checked and unchecked exceptions?

According to checked exception is an exception of a subclass other than subclasses and class Runtime Exception. The method which is used to throw IOException is read () of is an example of checked exception. In general, unchecked exceptions are RuntimeExceptions and its subclasses. Class error and its subclasses are the unchecked exceptions. The client programmers are not forced to declare in throws class or to catch the exception by the compiler with unchecked exception. Client programmer is not aware that the exception can be thrown. String’s charAt () method throws StringIndexOutOfBoundsException is an example. At the compile time, these checked exceptions are caught. Often, errors cannot be caught.

20. Define overriding?
If a method is declared by a class with the same return type, name and arguments as a method in the superclass then method class overrides the same which is present in superclass. If a method is invoked for object of a particular class then it is new definition of called method and not definition of method from superclass. Methods are overridden to be more public but not private.

21. Name the different types of inner classes?
• Member classes
• Anonymous classes
• Local classes and
• Nested top-level classes
Clearing the Java technical round is not an easy task and the candidate who is attending an interview on the Java platform must have a good knowledge on all the concepts. Interview is an opportunity had given to the student to explore his skills and talent by answering all the questions asked by the employer correctly. The candidate who is facing an interview can recollect all the concepts quickly by going through the interview questions and answers presented in this article.

C++ interview questions and answers


C++ interview questions

The interview questions and answers presented in this article are asked in the technical round of an interview by the employers. The student who is attending an interview in the software industry on C++ platform makes use of these questions. These interview questions are given best answers so that the candidate must give right answer to the employer. The candidate must give the answer confidently, so it is necessary to prepare well before facing an interview. These interview questions help in the preparation process and the students can revise all the concepts by going through these questions. These interview questions are the frequently asked questions by the employers in most of the interviews conducted by software companies.

1. What is C++?

C++ language was developed by Bjarne Stroustrup in AT&T Bell Labs which are an extension of C language. It is an object oriented programming language which is used for developing commercial and enterprise applications. Visual C++ of Microsoft became the best and perfect choice for the programmers and developers.

2. Mention the fundamental concepts of object oriented programming language?

It is mandatory to understand vital concepts which are highly used in the object oriented programming languages. Includes:
• Objects
• Classes
• Inheritance
• Encapsulation and data abstraction
• Polymorphism
• Message passing
• Dynamic binding

3. Define encapsulation?

Encapsulation is wrapping up of functions and data in a single unit. This single is nothing but a class. Information about an object is hidden such as code and the internal data structure in encapsulation.

4. What is an inheritance?

Inheritance is deriving a new class from the old class and the old class is known as base class whereas new class is known as derived class. The main usage of inheritance is reuse of the existing code than rewriting the code from scratch when it is required. In this process, object o one class obtains properties of other class.

5. Define polymorphism?

Polymorphism is one name with different forms. In the program, it permits you to have more than one function with same name. It helps in overloading so an operation is shown in different behaviors differently.
6. Define message passing?
A set of objects is present in an object oriented programs for communicating with each other. Specifying the name of object, information to be sent and the function name is included in message passing.
7. Define tokens in C++?

In a program, the smallest individual units are known as tokens. The following are the tokens of C++ programming language:
• Identifiers
• Strings
• Constants
• Keywords
• Operators

8. What is a constructor?

The member function which has a same name of its class is known as a constructor. When an object of a class is created then invoking of a constructor takes place. The name constructor is given because it constructs values of data members of class.

9. Where do you use enumerated data type?

Enumerated data type is a user defined data type which is used to attach names to numbers to increase unambiguousness of code. Lists of words are enumerated automatically by enum keyword by assigning then values 0, 1, 2, 3, etc.

10. Why the default constructor is used?

A default constructor is a constructor which does not accept any parameters is known as a default constructor.

11. Define destructor?
For an object class, a destructor is called when the object is out of the scope or it is deleted explicitly. As the name implies, the destructor is used to destroy objects that are created by the constructors. The destructor is also a member function like the constructor whose name is its class name but it is preceded by tilde.
12. Does variable declaration in C++ differ from C?

Yes. In the C language, variables are declared in the beginning of scope whereas in C++, anywhere in the scope variables can be declared. Understanding is made easy to the programmer as variables are declared in the context of usage.

13. Define a class?

A class is a template which contains data members and member functions.

14. Differentiate C and C++?

The main difference between C and C++ is C is a procedure oriented language whereas C++ is an objected oriented programming language. C language is considered as a super set of C++. Function overloading, inheritance and method overloading are not supported by C language whereas C++ supports them. In a C program, main function need not return a value whereas it must return a value in C++.

15. Define a copy constructor?

The constructor which has the same name of a class and which is used to copy the objects deeply is known as a copy constructor.

16. Define a scope resolution operator?
An identifier is referenced in the global scope which is hidden by other identifier with same name in local scope is allowed by the scope resolution operator.
17. Distinguish object and instance?

Object is an instance of user-defined type. From one class, multiple objects can be instantiated whereas an instance of a class is object.

18. Differentiate macro and inline?

• A strict parameter type checking is followed by inline but it is not followed by macro.
• Preprocessor is used to expand macros and the inline definitions may or may not be replaced by the compiler.

19. Define Multiple Inheritance?

The class which inherits or acquires properties from many classes then it is known as inheritance.
20. Define implicit conversion?

Automatic conversion is performed by C++ if the data type are mixed in the expression. Smaller type is changed to wider type. Integer converting to float type is an example.
21. In C++, give the usage of virtual destructor?
If the object is destroyed then the destructor is called automatically. In C++, virtual destructor is mainly used to avoid resource leaks by doing clean-up of an object.
22. In C++, what is a reference variable?

An alias is provided by a reference variable to a variable which is previously defined.

23. Describe virtual functions?

• The virtual functions must belong to particular class.
• They are not static members.
• Object pointers are used to gain access these virtual functions.
• A virtual function may be a friend of other class.

24. Mention inheritance advantages?

• Time is saved in developing a program.
• Code can be reused.

25. Define dynamic constructor?

While creating objects, memory is allocated using constructors. Objects are allocated memory at the construction time which is known as dynamic construction of objects. Here, allocation of memory can be done using an operator called new.

26. Why declaration is used?
Name is used from a namespace if it is declared.
27. Define conversion constructor?

The constructor which has a single parameter that is declared without using function specifier is known as a conversion constructor. The converting constructors are used to convert from first parameter type to converting constructor’s class type.

28. Define associative container?

Associative containers are specially designed to provide gain access to elements with keys. In general, the associative containers are of four types, they are:
• Map
• Set
• Multimap
• Multiset

29. Give some pure object oriented languages?

• Java
• Smalltalk
• Sather
• Eiffel
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