CLASS AND OBJECT

CLASS:-           CLASS IS ABSTRACT USER DEFINED DATA TYPE

                                   CLASS IS WAY OF BINDING DATA AND METHOD TOGETHER

                                   CLASS IS GROUP OF SIMILAR KIND OF OBJECTS

Defining a class in c++

Student

Roll Name Age Marks

Void get() // to accept student details Void show()// to display student details

If we have to define class in C++ for the above class represented in diagram we can define like this

#include<iostream.h>

#include<conio.h>

class student

{

int roll,age,marks;       // by default data are private, private data are not accessible out side class

char name[20];

public:                     // functions are public means it will be accessible outside the class using object of class

void get()

{

cout<<"\n enter roll";

cin>>roll;

cout<<"\n enter name";

cin>>name;

cout<<"\n enter age";

cin>>age;

cout<<"\n enter roll";

cin>>marks;

}

void show()

{

cout<<"Name:"<<name<<endl;

cout<<"Noll:"<<roll<<endl;

cout<<"Age:"<<age<<endl;

cout<<"Marks:"<<marks<<endl;

}

};

void main()

{

student s;

s.get();

s.show();

getch();

}

Here function is defined inside the class. We can also define function outside the class as give below

#include<iostream.h>

#include<conio.h>

class student

{

int roll,age,marks;                   // by default data are private, private data are not accessible outside class

char name[20];

public:                           // functions are public means it will be accessible outside the class using object of class

void get(); // function prototype

void show();// function prototype

};

void student::get() // function is define using scope resolution operator , student::get() mean get of student class

{

cout<<"\n enter roll";

cin>>roll;

cout<<"\n enter name";

cin>>name;

cout<<"\n enter age";

cin>>age;

cout<<"\n enter roll";

cin>>marks;

}

void student::show()               // function is defined  using scope resolution operator , student::show() mean show                                                    of student class

{

cout<<"Name:"<<name<<endl;

cout<<"Noll:"<<roll<<endl;

cout<<"Age:"<<age<<endl;

cout<<"Marks:"<<marks<<endl;

}

void main()

{

student s;

s.get();

s.show();

getch();

Access modifiers :- (or access specifiers) are keywords in object-oriented languages that set the accessibility of classes, methods, and other members.

1.    Public :- accessible every where

2.    Protected :- accessible inside the class and in derived class

3.    Private:- accessible only by member function of class.

Using class in main Program

Class can be used in main program by declaring object

Since private members are not accessible outside object can access only public member

As shown in given example

void main()

{

student s;          // s is object of class student

s.get();                    // accessing get function(using .dot operator) of student class as it is public

s.show();                // accessing show function(using .dot operator) of student class as it is public

getch();

}

Array of object

Student s can store details of one student. If we have to store details of more than one student we can create array of student object like

Student s[5];

We can call the function student[i].get()

Example

void main()

{

student s[5];          //five  object of class student

for(i=0;i<5;i++)

{

S[i].get();              

}

for(i=0;i<5;i++)

{

S[i].show();          

}

getch();

}

}