Page 483 - Computer science 868 Class 12
P. 483
void display() : Prints coefficients a, b and c and discriminant d
A derived class Roots is defined to calculate the roots of the quadratic equation (if possible) with appropriate message. The details
of the class is as follows:
Class name : Roots
Data Members
double r1, r2 : To store the roots
Member Methods
Roots(……) : Parameterised constructor to initialise variables of base and derived classes
void calculate() : Calculates the roots r1 and r2 of the equation using formula
b
−± b 2 − ac
4
x =
2 a
along with appropriate message as given below:
d < 0 Roots are imaginary
d = 0 Roots are real and equal
d > 0 Roots are real and unequal
void display() : Displays the roots r1 and r2 and the base class data
Using the concept of inheritance, specify the class Roots details of the constructor and the member functions void calculate() and
void display(). Base class and main method need not to be written.
7. A superclass Detail has been defined to store the details of a customer. Define a subclass Bill to compute the monthly telephone
charge of the customer as per the chart given below. [ISC 2012]
Number of calls : Rate
1 – 100 Only rental charge
101 – 200 60 paise per call + rental charge
201 – 300 80 paise per call + rental charge
Above 300 1 rupee per call + rental charge
The details of both the classes are given below.
Class name : Detail
Data Members/instance variables
name : to store the name of the customer
address : to store the address of the customer
telno : to store the phone number of the customer
rent : to store the monthly rental charge
Member Functions
Detail (…) : parameterised constructor to assign values to data members
void show () : to display the details of the customer
Class name : Bill
Data Members/Instance variables
amt : to store the amount to be paid by the customer
Member Functions
Bill (…) : parameterised constructor to assign values to data members of both
classes and to initialise amt = 0.0
void cal() : to calculate the monthly telephone charge as per the chart given above
void show() : to display the details of the customer and amount to be paid
Using the concept of inheritance, specify the class Bill giving details of the constructor(), void cal() and void show(). You need not
write base class and main method.
8. A super class Worker has been defined to store the details of a worker. Define a subclass Wages to compute the monthly wages
for the worker. The details/specifications of both the classes are given below.
Class name : Worker
Data Members/instance variables
name : to store the name of the worker
basic : to store the basic pay in decimals
Member Functions
Worker (…) : parameterised constructor to assign values to the instance variables
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Inheritance, Interfaces and Polymorphism 481

