Class:

A class is an expanded concept of a data structure: instead of holding only data, it can hold both data and functions.

An object is an instantiation of a class. In terms of variables, a class would be the type, and an object would be the variable.

Classes are generally declared using the keyword class, with the following format:

class class_name

{

 access_specifier_1:

 member1;

 access_specifier_2:

 member2;

 ...

 } object_names;

Where class_name is a valid identifier for the class, object_names is an optional list of names for objects of this class. The body of the declaration can contain members, that can be either data or function declarations, and optionally access specifiers.

For Example:

// classes example

#include 

using namespace std;

class Crectangle

{

 int x, y;

   public:

 void set_values (int,int);

 int area () {return (x*y);}

};

void CRectangle::set_values (int a, int b)

{

  x = a;

   y = b;

}

int main ()

{

  CRectangle rect;

  rect.set_values (3,4);

   cout << "area: " << rect.area();

  return 0;

}

Output:

12