What do you mean by Abstract class?

In what way is a class helpful in creating a user defined data type?

Design a class 'Time' with the following specifications:

class Time

Data members/Instance variables
int hour, min, sec

Member Methods:
void gettime( ) : to accept a time in hour, minute and second. void showtime( ) : to display the time in terms of hour, minute and second.

Write a main method to create an object of class 'Time' and call the member methods.

Design a class 'Rectangle' with the following specifications:

class Rectangle

Data members/Instance variables
int length, breadth, area, perimeter

Member methods:
void input( ) : to accept length and breadth of a rectangle.
void calculate( ) : to calculate area and perimeter of rectangle.
void display( ) : to print area and perimeter of rectangle.

Write a main method to create an object of class 'Rectangle' and call the member methods.