Class (C++)

Class

Class is a user defined data structure, it contains both data and functions. Lets take an example:

int x;  // 5;

class student;  // Saad, 101

In first case int is used because we only want to save an integer value but if we want to store a data consisting of more than one type like in case of a student which includes its name,roll number etc, then we will define our own data type i.e student. Below mentioned example gives a complete overview of a user defined data structure (Class).

Example

#include "stdafx.h"

#include "iostream"

#include "conio.h"

#include "string"

using namespace std;

// STUDENT CLASS, A STUDENT IS DEFINED IN TERMS

// OF ITS ATTRIBUTES I.E NAME, ROLL NUMBER ETC

class student

{

// ATTRIBUTES OF A STUDENT, THESE ARE DECLARED AS PRIVATE

private:

            string name;

            int rollNo;

// ALL FUNCTIONS OF A STUDENT CLASS

public:

            student();

            student(string,int);

            void setName(string);

            void setRollNo(int);

            string getName();

            int getRollNo();

            void display();

};

// CONSTRUCTOR 1

student::student()

{

           

}

// CONSTRUCTOR 2

student::student(string _name, int _rollNo)

{

            setName(_name);

            setRollNo(_rollNo);

}

// FUNCTION FOR SETTING THE NAME OF THE STUDENT

void student::setName(string _name)

{

            name = _name ;

}

// FUNCTION FOR SETTING THE ROLL NUMBER OF THE STUDENT

void student::setRollNo(int _rollNo)

{

            if ( _rollNo > 0 )

                        rollNo = _rollNo ;

}

// FUNCTION FOR RETURNING THE NAME OF THE STUDENT

string student::getName()

{

            return name;

}

// FUNCTION FOR RETURNING THE ROLL NUMBER OF THE STUDENT

int student::getRollNo()

{

            return rollNo;

}

// FUNCTION FOR DISPLAYING THE ATTRIBUTES OF A PARTICULAR STUDENT

void student::display()

{

            cout << "Student name    : " << getName() << endl;

            cout << "Student roll    #  : " << getRollNo() <<endl ;

}

// DRIVER PROGRAM

int main()

{

            student S1("Saad Bin Saulat",101);

            S1.display();

            student S2("Osama Shaukat",102);

            S2.display();

            student S3("Ayesha Khan",103);

            S3.display();

           

            _getche();

            return 0;

}

Output

Student name   : Saad Bin Saulat

Student roll    # : 101

Student name   : Osama Shaukat

Student roll    # : 102

Student name   : Ayesha Khan

Student roll    # : 103