Object Oriented Programming using C++.ppt

Object Oriented Programming
using C++

Overview
 Problem Solving
 Features of an OOL
 Basic Syntax
 Programming Paradigms

Solving a Programming Problem
 Analysis
 Design
 Coding
 Management
 Programming paradigms
 Programming languages

Concepts & Relationships
– A rectangle uses lines
– A circle is an ellipse
– A wheel is part of automobile
– A set creates its elements

Some Features of OOP languages
 An OOP language should support
– Easy Representation of
 Real-world objects
 Their States and Abilities
– Interaction with objects of same type
– Relations with objects of other type
– Polymorphism and Overloading
 Reusability of code
 Convenient type definitions

Basic Syntax
 Same as C
 Additional operators
 Additional keywords

Programming Paradigms
 Procedural Programming (functions)
 Modular Programming (namespaces)
 Object Oriented Programming (classes)
 Generic Programming (templates)

Procedural Programming
 A program is a list of instructions
 Concentration is on what is to be done?
 Problems created by global data
 No access control !!

Modular Programming
 namespace
 Example to learn the syntax : A toy math library.
– Matrix Module
 Allocate
 Transpose
 Print
– Vector Module
 Allocate
 Transpose
 Print

Declaration of namespaces
// in file stdmatrix.h
namespace Matrix
{
int** allocate(int r,int c);
void print(int **matrix,int r,int c);
};
// in file stdvector.h
namespace Vector
{
int *allocate(int size);
void print(int *vector,int size);
};

Definition of Matrix functions
int **Matrix::allocate(int r, int c)
{
int **mat;
mat = new int*[r];
for (int i = 0; i < r; i++)
mat[i] = new int[c];
return mat;
}
void Matrix::print(int **matrix,int r, int c)
{
for (int i = 0; i < r ; i++)
{
for (int j = 0; j < c ; j++)
printf("%d ",matrix[i][j]);
printf("n");
}
printf("n");
}

Definition of Vector functions
int *Vector::allocate(int size)
{
int *vec = new int[size];
return vec;
}
void Vector::print(int *vector,int size)
{
for (int i = 0; i < size; i++)
printf("%d ",vector[i]);
printf("n");
}

How to use Matrix and Vector ?
// in the file main.c
#include <stdmatrix.h>
#include <stdvector.h>
using namespace Matrix;
using namespace Vector;
main()
{
int **m = Matrix::allocate(3,4);
int *v = Vector::allocate(3);
Matrix::print(m,3,4);
Vector::print(v,3);
}

Adding functions to namespaces
 How does user add the transpose function
now ?
// in the file mymatrix.h
#include “stdmatrix.h”
namespace Matrix
{
int **transpose(int **matrix, int r, int c);
}

Adding definitions
// In the file mymatrix.cpp
#include “mymatrix.h”
int **Matrix::transpose(int **matrix, int r, int c)
{
// Code for transposing and returning the
// matrix.
}

Using the transpose()
// in the file main.c
#include <mymatrix.h>
#include <myvector.h>
using namespace Matrix;
using namespace Vector;
main()
{
int **m = Matrix::allocate(3,4);
// fill with some random data in the matrix.
int **tm = Matrix::transpose(m, 3, 4);
}

Object Oriented Programming
 Class
 Object
 Overloading (operators, functions)
 Inheritance

Class
 class : Definition of the entity
– A tool for creating new types
 Ex: Matrix and Vector
– Access Control
 public, private, and protected
– Constructors, Destructors
– Member functions

The Matrix Class Definition
class Matrix
{
private:
int **m;
public:
Matrix();
void print();
void transpose();
Matrix *transpose();
~Matrix();
}
 Access Control
 Constructor/Destructor
 Member Functions
– Ordinary Functions
– Overloaded Functions

Constructors
 Different Constructors for a class
– Matrix();
– Matrix(int init); // 0 = zero matrix, 1 = Identity!!
– Matrix(Matrix m);
 Writing a constructor

Objects
 Creation
– Named object, free-store object (new & delete),
non-static member object, an array element,
temporary object, …etc
 Destruction
 Copying Objects
– Direct assignment
– Copy Constructors - Matrix::Matrix(Matrix &m);

Creating Matrix Objects
Matrix m;
Matrix *m = new Matrix();
Matrix *n = m;
Matrix *n = new Matrix(m);
Matrix ma[10];
Matrix *mp = new Matrix[10];
Matrix *np = new Matrix[10](m);

Interacting with Matrix Objects
Matrix m;
m.transpose();
Matrix *n = m.transpose();

Functions
 Static functions
 Constant functions and mutable
 Inline functions
 Helper functions

Operators
 Member and Non-Member Operators
 Unary
 Binary
– Matrix & operator+= (Matrix a) // member
– Matrix Matrix::operator + (Matrix b) // member
– Matrix operator + (Matrix a, Matrix b) //non-member

A Code Example
class Complex
{
private:
int real;
int imaginary;
public:
Complex(int r, int i= 0): real(r),imaginary(i);
Complex(const Complex& a);
int re() const;
int im() const;
void operator += (Complex a);
Complex operator + (Complex b);
void print();
};

The Code..
Complex(const Complex& a)
{
real = a.real;
imaginary = a.imaginary;
}
int re() const
{
return real;
}
int im() const
{
return imaginary;
}

The Operator Code
void operator += (Complex a)
{
real += a.re();
imaginary += a.im();
}
Complex operator + (Complex b)
{
Complex nc(*this);
nc += b;
return nc;
}

Inheritance
 What is inheritance ?
 Parent and Derived
 Some properties of derived classes
– Constructors
– Member functions
– Overloading

Inheritance in C++
Class Rectangle : public Shape
{
}
Class Student : public Person
{
}
Public, protected and private !!

Multiple Inheritance
class Transmitter {
…
}
Class Receiver {
…
}
Class Radio : public Transmitter, public Receiver

Abstract Classes
class Shape
{
public:
virtual void rotate ( int )=0; // Make it pure !!
virtual void draw()=0;
}
Polymorphism through virtual functions ?

Virtual Base Classes
Base Base
| |
Derived1 Derived2
|__ Derived3 __|
 class Derived1 : virtual public Base
 class Derived2 : virtual public Base
 class Derived3 : public Derived1, public Derived2

Member Access Table
Derived with Private Base Protected
Base
Public Base
Private
Variables
X X X
Protected
Variables
private protected Protected
Public
Variables
private protected Public

Templates And Generic Programming
 Generic Functions and Classes
 template <class X> FUNCTION_NAME()
 Example :
– template <class X> void swap(X &a, X &b);
– template <class X, class Y>
void function(X &a, Y &b)

An example
template <class data_type> class List
{
data_type data;
List *next;
public:
List(data_type d);
data_type getdata();
}

Creating Template Objects
 A list of integers List<int> li;
 A list of doubles List<double> ld;
 A list of strings List<string> ls;
 A list of addresses List<address> ls;
– (where address is a predefined class/structure)

C++ I/O
 The <iostream>
 using namespace std;
 cout, cin, cerr
 ifstream, ofstream and fstream
Ifstream in;
in.open(const char *filename,openmode mode)
Mode can be ios:in, ios;out, ios:app,ios:binary,
…etc

File Reading and Writing
ifstream in;
double num;
char str[20];
in.read((char *)&num, sizeof(double));
in.read(str,10);
Using << and >> Operators.
in.getline();

The Standard Template Library
#include <vector>
vector <int> v;
Insertion, Access and Deletion:
push_back,pop_back,insert,front,size,..(see the manual)
Iterators vector<int>::iterator p = v.begin();
Other Templates :: List, Deque, Map….etc!!

Basic Exception Handling
 Try
 Throw
 Catch

Syntax
try
{
throw something;
}
catch (something)
{
// Do whatever has to be done here.
}
catch (…) :: Catches everything.

Object Oriented Programming using C++.ppt

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