Arrays can be used to represent a group of data items that belong to the same type, such as int or float .

If we want to represent a collection of data items of different types using a single name then we cannot use an array.

The data type which we use is known as structure. Structure is user defined data type.

struct struct_name

{

data_type member1;

data_type member2;

… …

};

//header files

#include<stdio.h>

#include<conio.h>

//Structure declaration

struct student

{

// data types & members

int rollno;

char name[20];

};

void main ()

{

struct student S1; //Structure variable

printf(“Input the name of student “);

scanf(“%d”,&S1.name);

printf(“Input the Roll number of student “);

scanf(“%d”,&S1.rollno);

printf(“name =%d“S1.name);

printf(“Roll number=%d“S1.rollno);

getch();

}

Input the name of student abc

Input the Roll number of student 1

name = abc

Roll number = 1

10 11 12 13 14 15 16 17 18 19

0 1 2 3 4 5 6 7 8 9

20 21

rollno

name

Unions are a concept borrowed from structures and therefore follow the same syntax as structures .

There is a major difference between them in terms of storage .

A union may contain many members of different types ,it can handle only one member at a time.

union union_name

{

data_type member1;

data_type member2;

… …

};

//header files

#include<stdio.h>

#include<conio.h>

//Union declaration

union student

{

// data types & members

int rollno;

char name[20];

};

void main (){union student S1; //Union variable printf(“Input the name of student “);scanf(“%d”,&S1.name);printf(“Input the Roll number of student “);scanf(“%d”,&S1.rollno);printf(“name =%d“S1.name);printf(“Roll number=%d“S1.rollno);getch();}

Input the name of student abc

Input the Roll number of student 1

name = abc

Roll number = 1

10 11 12 13 14 15 16 17 18 19

0 1 2 3 4 5 6 7 8 9

name

rollno

Classes are same as structure but with a small difference ie. Structure are having data only(int or float) but classes are having data and functions together.

The class has a mechanism to prevent direct access to its members ,which is the central idea of object-oriented programming.

Classes are user defined data types.In short structure + functions = classes.

Data

Functions Class

A class definition begin with the keyword class.The body of the class is contained with in the

brace { };

class <name of class>{ private: declaration of variables ; declaration of functions ; public: declaration of variables ; declaration of functions;};

//Header files

#include<iostream.h>

#include<conio.h>

class student //class declaration

{

private:

int rollno; // data members

char name[20];

public:

void getdata(); //functions

//defining member function inside the class definition

void display()

{

cout<<“Name=“<<name<<endl;

cout<<“Roll number=“<<rollno<<endl;

}

};

// defining member functions outside the class definition

void student :: getdata()

{

cout<<“Input the name of student”;

cin>>name;

cout<<“Input the roll number”;

cin>>rollno;

}

main()

{

cout<<“We are in main function “;

student S1; //creat object S1

S1.getdata(); //call member function

S1.display(); //call member function

getch();

}

Input the name of student abc

Input the roll number 1

Name = abc

Roll number = 1