Introduction to c programming

1
Unit - V
Introduction to c programming - object
oriented programming concepts - Structured
Vs OOP. Classes and objects - class
definition - Objects - class scope and
accessing members - access functions and
utility functions.
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• History of C
• Extension of C
• Early 1980s Bjarne Stroustrup (Bell
  Laboratories)
• Originally named C with Classes.
• Provides capabilities for object-oriented
  programming
• Objects reusable software components
• Model items in real world
• Object-oriented programs
• Easy to understand, correct and modify
• Hybrid language
• C-like style
• Object-oriented style
• Both

3
Object Oriented Programming

• OOP is a programming style that is focused on
  objects
• Important Features of OOP
• Abstraction
• Encapsulation
• Inheritance
• Polymorphism

4
Abstraction

• Showing only the essential features and hiding
  the unnecessary features
• The access modifiers in C or any OOP language,
  provides abstraction
• Functions also provide abstraction
• If a variable is declared as private, then other
  classes cannot access it
• The function name that is used in function call
  hides the implementation details from user. It
  shows only the outline of functionality that the
  function provides.

5
Encapsulation

• The process of bringing together the data and
  method of an object is called as encapsulation
• The data and method are given in the class
  definition
• Classes provides us with this feature -
  Encapsulation

6
Inheritance

• Feature that enables the characteristics or
  properties of a parent to reach its child
• C supports inheritance
• A class can inherit one or more classes
• Inherited class is called as parent class or
  super class or base class
• Class that inherits a parent class is called as
  child class or sub class or derived class

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Polymorphism

• Poly Many
• Morph Form
• Polymorphism is the characteristic that enables
  an entity to co exist in more than one form
• C supports function overloading and operator
  overloading to implement polymorphism

8
Structured Vs OOP
Structured OOP
Focuses on Process Focuses on Object
Follows Top Down Approach Follows Bottom Up Approach
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• Top Down approach
• A Single module will be split into several
  smaller modules
• General to Specific
• Bottom Up approach
• Lot of small modules will be grouped to form a
  single large module
• Specific to General
• If the requirements are clear at the first
  instance we can go for Top down approach
• In circumstances where the requirements may keep
  on adding, we go for Bottom up approach

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Structured Programming

• Using function
• Function program is divided into modules
• Every module has its own data and function which
  can be called by other modules.

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OBJECT ORIENTED PROGRAMMING

• Objects have both data and methods
• Objects of the same class have the same data
  elements and methods
• Objects send and receive messages to invoke
  actions

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I/O in C

• Since C is a superset of C, all of the C I/O
  
• functions such as printf and scanf which are
  found
• in the stdio.h header file, are still valid in
  C.
• C provides an alternative with the new stream
  
• input/output features by including iostream.h.

• Several new I/O objects available when you
  include the iostream header file. Two important
  ones are
• cin // Used for keyboard input
• cout // Used for screen output
• Both cin and cout can be combined with other
  member functions for a wide variety of special
  I/O capabilities in program applications.

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• Since cin and cout are C objects, they are
  somewhat "intelligent"
• They do not require the usual format strings and
  conversion specifications.
• They do automatically know what data types are
  involved.
• They do not need the address operator, .
• They do require the use of the stream extraction
  ( gtgt ) and insertion ( ltlt ) operators.
• The next slide shows an example of the use of cin
  and cout.

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Classes in C

• Class is defined as
• A collection of related variables and functions
  into a
• single structure
• A user-defined complex data type with its own
• operations

Object Instances of the class are called
objects. The variables and functions in the
definition of the class are called members.
Syntax to create a Class class class-name
private data and functions access-specifier
data and functions access-specifier
data and functions // ... access-specifier
data and functions object-list The
object-list is optional. If present, it declares
objects of the class.
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• access-specifier is one of these three C
  keywords
• public
• private (default)
• Protected
• private data can be accessed only by other
  members of the class.
• - public data can be accessed by other parts of
  the program
• - protected needed only when inheritance is
  involved.
• - access-specifier can be changed in any order,
  default is private.

Class Scope

• Class data members and member functions belong to
  that class's scope.
• Within a class's scope, class members are
  references by name.
• Outside a class's scope, class members are
  referenced through one of the handles on an
  object.

• Use dot (.) notation for object and references.
• Use arrow (-gt) for pointer to the object
• E.g.,
• c.x , cpt -gt x

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Implementation of a Class
Class declaration contains ? Declarations of
data members ? Prototypes (declarations) of
function members Definitions of function members
are not usually placed in class
declarationDefinitions placed outside the class
declaration must tell compiler where the
corresponding declaration/prototype is Use the
scope operator which has the
form ClassNameItemName
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1. Member functions "Inside" an object, so
don't pass object to them as a parameter. (They
receive the object to be operated on implicitly,
rather than explicitly via a parameter.)Non-membe
r functions "Outside" an object, so to operate
on an object, they must receive it via a
parameter. 2. Public items must be qualified when
referred to outside the class declaration Class
NameItemNamePublic constants are usually
declared static so they are global class
properties that can be accessed by all objects
of that class type rather than each object having
its own copy. 3. Simple member functions
Usually specified as inline functions. This
suggests to compiler to replace a function call
with actual code of the function with parameters
replaced by arguments saves overhead of
function call.
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Access Functions and Utility Functions

• Utility functions
• private functions that support the operation of
  public functions
• Not intended to be used directly by clients
• Access functions
• public functions that read/display data or check
  conditions
• For a data structure, it could call the isEmpty
  function

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Assignment - 5

1. Distinguish between a struct' and a class' in
   C?
2. How does a class accomplish data hiding? Explain
   with an example.
3. Explain the benefits of object oriented
   programming over procedure oriented programming
4. What are the access privileges in C? What is
   the default access level?
5. What do you mean by Encapsulation and explain in
   detail.
6. What is the difference between C structure and
   C structure.
7. Explain about the C classes in detail and
   design a class for playing cards?
8. Discuss in detail about utility functions and
   access functions.