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An activity is something people invest their spare time in.An activity
has a name and a number of participants Consider the following definition
of the class Activity
public class Activity {
protected:
String Name;
int NumberParticipants;
public:
Activity();
~Activity();
void InitiateActivity(); // Starts the activity.
}
(a)Define what is meant by the term inheritance with respect to
object oriented
programming.[2 marks ]
Inheritance is:
•The mechanism of creating a new class;(1 mark)
•that includes the member variables and methods of an existing
class.(1 mark)
[2 marks ]
(b)An exercise is a particular form of activity,with the added properties
of a
PainThreshold which is an integer in the range 1 to 100 and a number
of
Repetitions which is also an integer.Using inheritance,define a class
exercise
which incorporates all the attributes of an activity,as well as the
properties specific to exercises.The attributes should be made available
to subsequent derived classes, but not to unrelated classes.Your class
should also include a constructor which takes all the member attributes
as parameters.[4 marks ]
A sample definition
of exercise follows:
class excercise : public activity {
public:
excercise(int p, int r);
protected:
int PainThreshold;
int Repetitions;
}
And the following marking scheme should be used:
•Declaring the class to inherit from activity (1 mark)
•Declaring the members to be protected (1 mark)
•Including suitable declarations of the members;(1 mark)
•Including an appropriate public constructor.
[4 marks ]
(c)A hobby is also a particular form of Activity with the added attribute
of a Cost which is an integer.An implementation of the hobby class
would include these members,along with a constructor which took the
member attributes as parameters. If a sport is both a hobby and an
exercise then the class sport can be derived from the combination
of the two classes exercise and activity
(i)State the object oriented name for this situation.[1 mark ]
(ii)List,with their types,the members variables (properties)which
are inherited by the class sport [5marks ]
(iii)Implement a constructor function for the class sport such that
it takes as
parameters all the member variables,and calls immediate parent constructors
with the appropriate parameters.In addition to this,you should initialise
the
number of participants appropriately.[3 marks ]
(i)Multiple
inheritance [1mark ]
(ii) •Name (String);(1 mark)
•NumberParticipants (int);(1 mark)
•PainThreshold (int);(1 mark)
•Repetitions (int);(1 mark)
•Cost (int).(1 mark)
[5 marks ]
(iii)A sample definition of the constructor follows:
sport(String Name,
int NumberOfParticipants,
int PainThreshold,
int Repetitions,
int Cost) {
excercise(Name, PainThreshold, Repetitions);
hobby(Name, Cost);
NumberParticipants= NumberOfParticipants;
}
And the following marking scheme should be used:
•Calling the exercise constructor with the appropriate parameter
list;
(1 mark)
•Calling the hobby constructor with the appropriate parameter
list;(1 mark)
•Initialising the NumberParticipants member.(1 mark)
[3 marks ]
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