OOP in C++

IN THE NAME OF GOD

OOPin C++Maysam Rajaati Farid Bekran

111/27/2008

Tabriz University - Iran

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TABLE OF CONTENTS

1. History2. Philosophy of C++ & increments of C3. Classes in C++4. Objects in C++5. Access Specifiers6. Class & Object memory allocation7. Static data (In classes)8. Inheritance(Single)9. Inheritance(multiple)10.INCLUSIVE CLASSES11.POLYMORPHISM12.COMPILERS

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HISTORY It was developed by Bjarne Stroustrup in1979 at Bell Labs. As an enhancement to the C programming language and originally named "C with Classes". It was renamed to C++ in 1983.

C++

C Simula CLUSmallTalkAlgol68ADA83 ML

C# JAVA DPerlPHPADA95

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PHILOSOPHY OF C++ & INCREMENTS OF C C++ is designed to be a statically typed general-purpose language that is as efficient and portable as C

C++ is designed to directly and comprehensively support multiple programming styles (procedural programming, data abstraction, object-oriented programming, and generic programming)

C++ avoids features that are platform specific or not general purpose

CC++

Templates

class

Operator overloading

Virtual functions

Multiple inheritance

Exception handling

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CLASSES IN C++ Classes are User defined types. Classes are for Encapsulate our data. Classes hold both data and function on data.

class CPolygon{ private: int Width; int Height; // You can remove “private”

public: Cpolygon() // Has no return value { } int Area()

{ } void Draw()

{ } ~Cpolygon() // Has no Parameter , Has no return value { } };

CPolygon

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OBJECTS IN C++

Some Data

Definition of class

Some Data

1000

Some Data

10230

Objects of Class

Definition of a class only is the class Specification. Object of a class allocate real memory for members.

Example:…Cpolygon obj1; // call the user defined constructorObj1.Draw(); // draw the obj1 to screencout << Obj1.Area(); //prints the area of polygon obj1

// if scope ends the destructor called…

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ACCESS SPECIFIERS

private

public

protected

Cpolygon objB

Class Cpolygon

NO

T A

LLOW

ED

Example 1 :…Cpolygon obj1;cout << Obj1.Width; // ERROR!obj.Draw(); //True! …

Example 2 :…class CPolygon{ void Draw() { cout << Width << Height; // True }…

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CLASS & OBJECT MEMORY ALLOCATION

Data 1

Data 2

Data 1

Data 2

Data 1

Data 2

Function 1

Function 2

Object 1 Object 2 Object 3

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STATIC DATAS(IN CLASSE)

Data 1

Data 2

Normal data

Data 3

Data 4

Static data

Object 1Object 2

Object 3

Data 1

Data 2

Normal data

Data 1

Data 2

Normal data

Class A{… //public Static int x;//declaration… };int A::x = 0;//definitionMain(){ cout << A::x; // access to static member …}

Static members use the access Secifiers of other members.

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STRUCTURES & CLASSES

Structure members are by default public but in class members are by default private.

Structures inherited publicly by default but classes inherited privately.

Difference between class and struct

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INHERITANCE

Single Inheritance

A

B C

Multiple inheritance

A

B C

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INHERITANCE(SINGLE)

Feature A

Feature B

Feature C

Base Class

Feature A

Feature B

Feature CFeature D

Derived ClassD

efined in B

ase Class

Defined in

Derived C

lass

Arrow means Derived from

class CPolygon{ protected : int Wedth; int Height; public: int Area()

{ } int Draw()

{ } };class CRectangle : public CPolygon{ };

CPolygon

CRectangle

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INHERITANCE(SINGLE)Access Specifier

private

public

protected

private

public

protected

Base objB

Class Derived

Derived objD

Class Base

Base class has no access to derived class

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INHERITANCE(SINGLE)Public & Private Inheritance

Class C: private A

B objB

Class B : public A

private

public

protected

class A

private

public

protected

A objA

private

public

protected

C objC

NO

T A

LLO

WE

D

Public & Private Inheritance are methods that control Objects accessibility to parent public members.

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INHERITANCE(SINGLE)Overloading functions in base and derived class

Inplemention…CRectangle objREC; Cpolygon objPOL;objREC.Draw(); objPOL.Draw();…

Class Cpolygon { … public: void Draw() { cout << “Drawing Cpolygon”<< “\n”;}};Class CRectangle : public Cpolygon{ … public: void Draw() { // use the suitable draw steps }}

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INHERITANCE(MULTIPLE)

Base class A Base class B

Derived class C

class A{ };class B{ };class C : public A , public B{ };

Overloading functions in this kind of inheritance is like single inheritance.

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INHERITANCE(MULTIPLE)Ambiguity

class A{ public: void show() { cout << “in A class”;}; };class B{ public: void show() { cout << “in B class”;}; };class C : public A , public B{ // this class has no method with show() signature };

Implementation :…C object;object.show(); // compile errorObject.A::show(); // TrueObject.B::show(); // True …

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INCLUSIVE CLASSES

Class Wing

Class Bird

Class Wing

Class Hen

Class Wing

class wing { };class bird{

…wing obj; //bird has wing…

};class hen : public bird{ }; // hen derived from bird

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POLYMORPHISM

Polymorphism

Dynamic Static

Uses function overloading Compile time

Uses virtual function members Run-time

class Cpolygon{ … virtual void Draw() { } …}Cpolygon* ptrs[100];… // fill the ptrs[100]for(int i=0 ; i<100 ; i++) ptrs[i] -> draw();

If you don’t use virtual keyword on base class function, call line of “for” statement will call the base class function in every step.

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COMPILERS

Dev C++ (open source) - Free Microsoft Visual studio 2003 / 2005 / 2008 / 2010 - commercial Borland C++ builder - commercial Borland Turbo C++ explorer 2006 (Japanese , French , English ) - Free Apple C++ IBM C++ Intel C++ for Linux Sun Studio

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REFERENCES

1. Lefor, Robert W. Object Oreinted Programming in C++, 3rd ed.2. pratt, terans w. Programming language.3. www.wikipedia.com4. www.cplusplus.com

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