FAQ’s on C++:
1.
Basic
of C++
a)
Procedure Oriented
Programming
b)
Applications of C++
c)
Tokens, Expressions and Control
Structures
2.
Functionsin
C++
a)
Introduction Of Functions
b)
Inline Functions and Function
Overloading
3.
Classes
and Objects
a)
Introduction of classes and objects
b)
Friend Function
4.
Constructors
and Destructors
a)
Introduction of constructors
b)
Copy constructors
c)
Destructors
5.
Operators
overloading and Type Conversions
6.
Inheritance:
Extending Classes
a)
Types of Inheritance
b)
Virtual Base Classes
c) Abstract
Classes
7. Pointers, Virtual Functions and
Polymorphism
8. Managing Console I/O Operations
BASIC
OF C++
APPROACH
TOWARDS C++:-
1. What is procedure-oriented programming?
Ans:-Procedure
oriented programming basically consists of writing a list of instructions (or
actions) for the computer to follow,and organizing these instructions into
groups known as functions.
Also in
procedure oriented programming, the program is divided into procedures that do
discrete tasks. Each procedure has its own local data. Parameters are passed
between procedures for information communication.
2.What are the characterics of procedure oriented
programming?
Ans:-Characteristics
are:-
a) Emphasis on
doing things (algorithms).
b) Large
programs are divided into smaller programs known as functions.
c) Most of the
functions share global data.
d) Data move
openly around the system from function to function.
e) Employs
top-down approach in program design.
3.) What is object oriented
programmming?
Ans:-It is an
approach that provides a way of modularizing programs(dividing program into modules) by creating partitioned memory area
for both data and functions that can be used as templates for creating copies
of such modules on demand.
4.) What are the characteristics of object-oriented
programming?
Ans:-Characteristics
are:-
a)
Emphasis is on data rather than procedure.
b)
Programs are divided into what are known as functions.
c)
Data structures are designed such that they characterize the
objects.
d)
Data is hidden and cannot be accessed by external functions.
e)
Follows bottom-up approach in program design.
5.) What are
the advantages of inheritance?
AnsIt permits code reusability.
Reusability saves time in program development. It encourages the reuse of
proven and debugged high-quality software, thus reducing problem after a system
becomes functional.
6.)What is Polymorphism?
Ans-Polymorphism
is phenomena by which we can make make a method for reuse. Polymorphism is an
object oriented term. Polymorphism may be defined as the ability of related
objects to respond to the same message with different, but appropriate actions.
In other words, polymorphism means taking more than one form. Polymorphism
leads to two important aspects in Object Oriented terminology - First one is
function Overloading and second is function overriding. Overloading is the
practice of supplying more than one definition for a given function name in the
same scope. The compiler is left to pick the appropriate version of the
function or operator based on the arguments with which it is called. Overriding
refers to the modifications made in the sub class to the inherited methods from
the base class to change their behavior.
7.) What are Templates?
Ans-C++ Templates
allow u to generate families of functions or classes that can operate on a variety of different data types,
freeing you from the need to create a separate function or class for each type.
Using templates, u have the convenience of writing a single generic function or
class definition, which the compiler automatically translates into a specific
version of the function or class, for each of the different data types that
your program actually uses. Many data structures and algorithms can be defined
independently of the type of data they work with. You can increase the amount
of shared code by separating data-dependent portions from data-independent
portions, and templates were introduced to help you do that.
8.) What is abstraction?
Ans:- Abstraction is the basically type of process, It is the process of hiding the details and exposing only the essential features of a particular concept or object.
9.)Explain why encapsulation is required?
Ans-Encapsulation basically defined as :
> Encapsulation general meaning is information hiding.
> The purpose of efficiency of memory and speed.
> The data and code binds together.
> It is an OOP principle of placing the data and functionality within a single entity.
> it is to protect data from the client using the classes but still allowing the client to access the data, but not modify it.
10.)Name some pure object oriented
languages.
Ans- Smalltalk,
Java, Eiffel, Sather.
11.)What is the use of Microsoft foundation class library?
Ans- The Microsoft Foundation Class Library also called as A Microsoft Foundation Classes or MFC. It is basically a library that wraps portions of the Windows API in C++ classes, and including functionality that enables them to use a default application framework. Classes are defined for many of the handle-managed Windows objects and also for predefined windows and common controls. MFC library would help us reduce the code and development time.
12.)What is the difference between static link library and dynamic link library?
Ans-Basic diff are there :
> Static libraries are linked at compile time.
> Dynamic libraries are linked at runtime.
OVERVIEW OF C++:-
1. What is C++?
Ans:-Releasedin 1985,
C++ is an object-oriented programming language created by Bjarne Stroustrup.
C++ maintains almost all aspects of the C language, while simplifying memory
management and adding several features - including a new data type known as a
class (you will learn more about these later) - to allow object-oriented
programming. C++ maintains the features of C which allowed for low-level memory
access but also gives the programmer new tools to simplify memory management.
C++ is a powerful general-purpose programming
language. It can be used to create small programs or large applications. It can
be used to make CGI scripts or console-only DOS programs. C++ allows you to
create programs to do almost anything you need to do. The creator of C++,
Bjarne Stroustrup, has put together a partial list of applications written in
C++.
2.) What is Difference between C/C++?
Ans-1. In C
passing value to a function is "Call by Value" whereas in C++ its
"Call by Reference"
2.C does not have
a class/object concept. C++ provides data abstraction, data encapsulation, Inheritance
and Polymorphism.
3.C++ supports
all C syntax. File extension is .c in C while .cpp in C++.(C++ compiler compiles the files with
.c extension but C compiler cannot!)
4.In C structures
cannot have functions declarations. In C++ structures are like classes, so
declaring functions is legal and allowed.
5.C++ can have
inline/virtual functions for the classes.
6.C++ is C with
Classes hence C++ ; while in c the closest u can get to an User defined data
type is struct and union.
3.) Difference between "C structure"
and "C++ structure".
Ans:-Many diff are there :
1. Structure in C defined as limited to
within the module and cannot be initialized outside but Structure in C++ can
initialize the objects anywhere within the boundaries of the project.
2. C++ have a many methods((Procedures) but
in C no methods are there.
3. By default C structure are Public
and C++ structure are private .
4. C does not support Methods inside structure but C++ does.
5. In
C++ structure we can add functions but in Cstructure we can't.
6. In C++, structure behaves like class like can add function, and can
use properties on class as inheritance, virtual,etc,
But in C, structure we can have only data
member but not functions.
7. Structures in c++ doesnot provide datahiding but a class provides.
8.
classes support polymorphism, But Structures don't.
4.)What are the disadvantages of C++?
Ans- Disadvantages: 1. It's not pure object oriented programming language.
2. Its a Platform dependent
3.C++ does not give excellant graphics as
compare to java.
> Its Not case sensitive.
> C++ have Less features as comapred to
Java& C#.
> Its Not applicable in web enviornment.
> Does not provide very strong
type-checking.
> c++ code is easily prone to errors
related to data types, their conversions.
> Does not provide efficient means for
garbage collection.
>
No built in support for threads.
5.)How does a main() function in C++ differ from main() in C?
Ans-In C the default return type of main is void while in C++ the default return type is int.
6)What is difference between visual c++ & ANSI c++ ?
Ans:- Visual C++ is probably the most popular favored compiler, because of it's history of quality and stability. But in ANSI C++ is a less popular, but is a much more powerful and robust compiler. The IDE is also a lot more powerful than MSVC.
7.)Why is iostream better than stdio?
Ans-Iostream is better than stdio like that :
> The <iostream> library offers two major advantages compared to C's <stdio.h>:
it can be extended to support user-defined types. And it's type-safe. If programmer can give a complain about <Isostream> have give a poorer performance and a bloated ,And unintuitive interface.
8.)Why do we need the preprocessor directive #include <iostream>?
Ans:-This is because this directive causes the preprocessor to add the contents of the iostream file to the program. It contains declarations for the identifier cout and the operator <<.
9.) What is namespace?
Ans:-Namespaces basically
provide a simple method for qualifying element and attribute names used in
Extensible Markup Language documents by associating them with namespaces
identified by URI references. Its allow to group entities like classes, objects
and functions under a name. This way the global scope can be divided in
"sub-scopes", each one with its own name. It is an abstract container
providing context for the items. it holds and allowing disambiguation of items
having the same name.
TOKENS
, EXPRESSIONS AND CONTROL STRUCTURES:-
1.What are tokens?
Ans:-The smallest individual units in a progr am are known as tokens.C++ has following tokens:-
a)Keywords
b)Identifiers
c) Constants
d) Strings
e) Operators
2.What do you understand by dynamic initialization of variables?
Ans:-It refers to initialization run of variables at run time. In C++, a variable can be initialized at run time at the place of declaration.
3.What is a reference variable? What is its major use?
Ans:- A reference variable provides an alias (alternative name) for a previously defined variable. For ex:- if we make the variable average a reference to the variable mean, then both can be used interchangeably to represent that variable.
4.)Explain the scope resolution operator?
Ans-scope resolution operator permits a program to reference an identifier in the global scope that has been hidden by another identifier with the same name in the local scope.
5.) what are manipulators?
Ans-Manipulators are operators that are used to format the data display. The most commonly used manipulators are endl and setw.
6.)Name the operators that cannot be overloaded?
Ans:-The Name of operatores are there which can nt be overladed .......
> sizeof,
> [.]
> *
> -
> ::
> ?:
7.)What is a modifier?
Ans-A modifier as a modifying function is a member function which changes the value of at least one data member. In other words, we can say an operation that modifies the state of an object. Modifiers are also known as �mutators�.
8.)
What is
the difference between realloc() and free()?
Ans realloc():
> It is used to free the memory in the
program.
> This function is used to resize
memory.
> realloc() means it giving string
variables into the existed memory
free():
> Basically It is a macro. Macro used to
deallocate memory.
> free() function is used free the
memory which is allocated by malloc(),calloc() functions.
> free() means it empties the array.
9.) What is the difference between char str, char *str and char* str? Explain the meaning of char* or int* ?
Ans:-Char *str is just a pointer its can't store anything, If we cout or printf() char *str it prints till it finds termination char '';
char str is a char variable which is capable to store one character and store a string also. Its length can be fixed only at run time.Char* is pointer which store address of char variable .
FUNCTIONS IN C++:-
INTRODUCTION OF FUNCTIONS:-
1. What are the advantages of functions prototypes in C++?
Ans:- The function prototype describes the function interface to the compiler by giving details such as the number and the type of arguments and the type of return values.With function prototyping , a template is always used when declaring and defining a function. When a function is called , the compiler uses the template to ensure that proper arguments are passed , and the return value is treated correctly. Any violation in matching the arguments or the return types will be caught by the compiler at the time of compilation itself.
2.What is the main advantage of passing arguments by reference?
Ans:- Reference variables in C++ allows us to pass parameters to the functions by reference. When we pass arguments by reference , the ‘formal’arguments in the called function become aliases to the ‘actual’ arguments in the calling function. This means that when the function is working with its own arguments, it is actually working on the original data.
3.When do we need to use default arguments in a function?
Ans:-Default arguments are useful in situations where some arguments always have the same value.
4.)What
is the difference between declaration and definition?
Ans-The declaration tells the compiler that at some later point we plan to present the definition of this declaration. E.g.: void stars () //function declaration
The definition
contains the actual implementation.
E.g.:
void stars () // declaratory
{
for(int j=10; j > =0; j--) //function body
for(int j=10; j > =0; j--) //function body
cout << *;
cout << endl; }
INLINE FUNCTIONS AND FUNCTION OVERLAODING:-
1.Define inline functions?
Ans:-An inline function is a function that is expanded in line when it is invoked. That is , the compiler replaces the function call with the corresponding function code. All inline functions must be defined before they are called.
2.When will we make a function inline?
Ans:-To eliminate the cost of calls to small functions , we make the function inline.
3.How does an inline function differ from a preprocessor macro?
Ans:-Inline function is just like a normal function however macros are not really functions and therefore usual error checking does not occur during compilation.
4.What do you mean by overloading of a function?
Ans:-It refers to use of the same function name to create functions that perform a variety of different tasks.
5.)What
is function overloading and operator overloading?
Ans-Function overloading: C++ enables
several functions of the same name to be defined, as long as these functions
have different sets of parameters (at least as far as their types are
concerned). This capability is called function overloading. When an overloaded
function is called, the C++ compiler selects the proper function by examining
the number, types and order of the
arguments in the call. Function overloading is commonly used to create
several functions of the same name that perform similar tasks but on different
data types.
Operator overloading allows existing C++ operators to be redefined so that they work on objects of user-defined classes. Overloaded operators are syntactic sugar for equivalent function calls. They form a pleasant facade that doesn't add anything fundamental to the language (but they can improve understandability and reduce maintenance costs).
Operator overloading allows existing C++ operators to be redefined so that they work on objects of user-defined classes. Overloaded operators are syntactic sugar for equivalent function calls. They form a pleasant facade that doesn't add anything fundamental to the language (but they can improve understandability and reduce maintenance costs).
6.)What is the difference between "overloading" and
"overriding"?
Ans:
Many Differeces are there-
Many Differeces are there-
Overloading a method (or function) in C++
is the ability for functions of the same name to be defined as long as these
methods have different signatures (different set of parameters).
Method overriding is the ability of the
inherited class rewriting the virtual method of the base class.
overridding is runtime polymorphism while
overloading is compile time polymorphism.
CLASSES AND OBJECTS:-
1.Explain the concept of classes?
Ans:- A class is a way to bind the data
and its associated functions together. It allows the data (and functions) to be
hidden , if necessary,from external use. When defining a class , we are
creating a new abstract data type that can be treated like any other built-in
data type.
2.)What is the difference between class and structure?
Ans:-Diff b/w Class and Structure is :
Class is difined as-
>Class is a successor of Structure. By default all the members inside the class are private.
>Class is the advanced and the secured form of structure.
>Classes are refernce typed.
>Class can be inherited.
>In Class we can initilase the variable during the declaration.
>Class can not be declared without a tag at the first time.
>Class support polymorphism.
Structure difine as :
> In C++ extended the structure to contain functions also. All declarations inside a structure are by default public.
> Structures contains only data while class bind both data and member functions.
> Structure dosen't support the polymorphism, inheritance and initilization.
> Structure is a collection of the different data type.
> Structure is ovrloaded.
> Structures are value type.
> Structure can be declared without a tag at the first time
3.What are objects?
Ans:-Objects are the instance of the class.They are dynamic.They are the basic runtime entities in an object-oriented system.They may represent a person,a place,a bank account,a table of data or any item that the program has to handle.
4.When do we declare a member of a class static?
Ans:-We declare a member of a class as a static to maintain values common to the entire class.A static member can be used as a counter that records the occurrences of all the objects.
5.What is public, protected, private?
Ans:-Public variables - that are visible to all classes.
Private variables - that are visible only to the class to which they belong.
Protected variables - that are visible only to the class to which they belong, and any subclasses.
6.What are local classes?
Ans:-Classes which are defined and used inside a function or a block are known as local classes. Local classes can use global variables(declared above the function) with the help of scope operator and the static variables declared inside the function but cannot use automatic local variables.
FRIEND FUNCTION:-
1.What is a friend function?
Ans:-The functions that are declared with the keyword friend are known as friend function. A function can be declared as a friend in any number of classes. A friend function, is not a member function, but it has full access rights to the private members of the class.
2.What are the features of the friend function?
Ans:-Features of the friend function are:-
a) It is not in the scope of the class to which it has been declared as friend.
b) It cannot be called using the object of that class.
c) It can be invoked like a normal function without the help of any object.
d) Unlike member functions, it cannot access the member names directly.
e) It can be declared either in the public or the private part of a class without affecting its meaning.
f) Usually,it has objects as arguments.
CONSTRUCTORS AND DESTRUCTORS:-
1. What is a constructor?
Ans:-It is a special member function
whose task is to initialize the objects
of its class.It is of the same name as the class. It is invoked whenever an
object of its associated class is created . It constructs the values of data
members of the class.
2.What is a copy constructor?
Ans:-A constructor which can accept a
reference to its own class as a parameter is known as the copy constructor.
3.What is a parameterized constructors?
Ans:-The constructors that can take
arguments are called parameterized constructors.
4.What do you mean by dynamic
initialization of objects?
Ans:-It means the initial value of an
object may be provided during run time. It provides flexibility of using
different format of data at run time depending upon the situation.
5.What is destructor and what is its
role?
Ans:-A destructor is a member function
whose name is the same as the class name but is preceded by a tilde. It is used
to destroy the objects that have been created by a constructor. A constructor
never takes any argument nor does it return any value.
6.Difference between a "assignment operator" and a
"copy constructor"
Ans:-many diff are there :
> Assignment operator assign the object of one object to
another aftr the 1st object is fully created but in copy constructor it
assign the value of one object to another at the time of its
creation .
> The copy constructor is use for initialising a new instance
from an old instance, And is called when passing variables by value into
functions
or as return values out of functions. but in Assignment operator
is used to change an existing instance to have the same values as the rvalue,
which means that the instance has to be destroyed and re-initialized if it has
internal dynamic memory.
> Copy constructor
copies a existing object to a non existing object, which we are going to
create. Assignment operation can happen between two existing objects.
> The copy constructor is creating a new object. But in The
assignment operator has to deal with the existing data in the object.
> Copy constructor creates shallow copy but in assignment
operator creates deep copy.
> The copy constructor is called at initialising the object
but the assignment operator is used to assign one object to another.
> Copy constructor donot return anything. But in
Assignment operator returns object of same type.
> The copy constructor
initializes uninitialized memory,
But in assigenment operator starts with an existing initialized objects.
> Copy constuctor initialize the
object with the another object of same class But assignment operator can be
called on objects of different classes .
OPERATOR OVERLOADING
1.What is operator overloading?
Ans:-The mechanism of giving special meanings
to an operator is known as operator overloading.
2.Why is it necessary to overload an
operator?
Ans:-Operator overloading provides a
flexible option for the creation of new definitions for most of the C++
operators. We can almost create a new language of our own by the creative use
of the function and operator overloading techniques.
INHERITANCE:EXTENDING CLASSES
1.What does inheritance mean in C++?
Ans:- Inheritance is the process by
which objects of one class acquire the properties of objects of another class.
It provides the idea of reusability.
2.What are the different forms of
inheritance? Give example for each.
Ans:-The different forms of inheritance are as follows:-
a) Single Inheritance :- A derived class
with only one base class is called single inheritance.
b) Multiple Inheritance:-A derived class
with several base classes is called multiple inheritance.
c) Hierarchical Inheritance:- The class
acting as a base class for different derived classes is known as hierarchical
inheritance.
d) Multilevel Inheritance:-The mechanism
of deriving a class from another derived class is known
as multilevel inheritance.
e) Hybrid Inheritance:-The mechanism of
deriving a class from a base class and two derived classes is known as hybrid
inheritance.
3. What is virtual class and friend class?
Ans:
friend class is the bassically which class used when two or more classes are designed to work together.used to share private data between 2 or
friend class is the bassically which class used when two or more classes are designed to work together.used to share private data between 2 or
more classes the function declared as freind are not called
using any object it is called like normal . But in virtual class is whihc class
aids in multiple inheritance, it is used for run time polymorphism when object
is linked to procedure call at run time.
4.When should you use multiple inheritance?
Ans:
There are three acceptable answers:- "Never," "Rarely," and "When the problem domain cannot be accurately modeled any other way."
There are three acceptable answers:- "Never," "Rarely," and "When the problem domain cannot be accurately modeled any other way."
Consider an Asset class, Building class, Vehicle class, and
CompanyCar class. All company cars are vehicles. Some company cars are assets
because the organizations own them. Others might be leased. Not all assets are
vehicles. Money accounts are assets. Real estate holdings are assets. Some real
estate holdings are buildings. Not all buildings are assets. Ad infinitum. When
you diagram these relationships, it becomes apparent that multiple inheritance
is a likely and intuitive way to model this common problem domain. The
applicant should understand, however, that multiple inheritance, like a
chainsaw, is a useful tool that has its perils, needs respect, and is best
avoided except when nothing else will do.
5.What is an orthogonal base class?
Ans:
Its a normally a base class if two base classes have a no overlapping properties methods they are said to be orthogonal to each other. A class can be derived from these two base classes with no difficulty.
Its a normally a base class if two base classes have a no overlapping properties methods they are said to be orthogonal to each other. A class can be derived from these two base classes with no difficulty.
6.What are abstract base classes?
Ans:
Abstract Base Classes are classes which cannot be used to create any objects.
Abstract Base Classes are classes which cannot be used to create any objects.
7.What is containership?
Ans:
Containership is bassically type of hierarchy. It can also be called containment hierarchy. In C++ Possessing of objects of other classes in a class is called containership or nesting.
Containership is bassically type of hierarchy. It can also be called containment hierarchy. In C++ Possessing of objects of other classes in a class is called containership or nesting.
8.How can a base pointer access the members of a derived class?
Ans:
Base pointer is only point to the object of derived class but it cannot access the members of the derived class .
Base pointer is only point to the object of derived class but it cannot access the members of the derived class .
9.Describe the syntax of the single inheritance.
Ans:-class
derived-classname : visibility-mode base-class-name
{
……//
…..// members of derived class
….//
};
10.What is a
virtual base class?
Ans:-Multipath
inheritance may lead to duplication of inherited members from base class.This may be avoided by making the
common base class as virtual base class.
POINTERS,VIRTUAL FUNCTIONS AND
POLYMORPHISM
|
1.What is Pure Virtual Function? Why and when it
is used ?
|
||||
|
Answer:
The abstract class whose pure virtual method has to be implemented by all the
classes which derive on these. Otherwise it would result in a compilation
error.
This construct should be used when one wants to ensure that all the derived classes implement the method defined as pure virtual in base class.
|
REFERENCES:-
book-ebalaguruswamy
.
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