Object Oriented Programming (OOP) Aug 6th

OOP's....OOP is a subject, no need to panic

Defination

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OOP is a programming methodology that helps organize the computer program through the use of inheritance, encapsulation and polymorphism.

OOP was introduced to organize complex programs.

WAY TO OOP(C++ and Java)

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1970 - Dennis Ritchie - C

1979 - Bjarne Stroustrup- C with classes

1983 - Renamed it to C++

But as C++ could not support world wide web(WWW)....(Yeah...the internet u are doing now....ORKUTING...Got IT!!)....something new was required

1991-92 - Oak (sir called it OOOOaaaak, why not oak ,I dont know...)

1995 - Java(Oak renamed with more flexibility)

1. Procedural Programming- code based

2. Object oriented Programming- Data Based

Principal of OOP

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1. Encapsulation

2. Inheritance

3. Polymorphism

Encapsulation - Protects the data from unauthorized use. JUST LIKE A CAPSULE

Inheritance - Property by which one objects acquire the properties of other. Like a subclass inherits the properties of superclass.

Polymorphism - In hindi....."Ek naam anek kaam" . Thats what it is....

A feature to be used in general class of actions. The action however depends on the nature of situation.

One example of polymorphism(as given by sir)

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Suppose u are reading a book(most likely a comics) and ur mom calls u to take ur dinner, then what will u do is that u will reading 1 or 2 more pages and then leave for dinner. But just in case it was a Phone call u would have rushed for it, irrespective of the interest you were getting, while you were reading.

GOT MY POINT!!

Data Types

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Integer-> long(64), int(32), short(16), byte(8)

Floating-> Float(32), Double(64)

Character-> Char(16)

Boolean-> True, False

Array

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type variable-name[]=new type[size]

Ex-

1D array:

int month_days[]=new int[4];

2D array:

int twoD[][]=new int[4][5];

function of new operator

->allocates memory at runtime

->so it is dynamic memory allocation

import java.io.*;

class array{

public static void main(String args[])

{

int month_days[]=new int[4];

month_days[0]=31;

month_days[1]=28;

month_days[2]=31;

month_days[3]=30;

s.o.p("April has"+month_days[4]+month_days[3]+"days");

}

}

public->access specifier

to compile:

c:\javac array.java

to execute

c:\java array

Static methods are executed first at the run time.