Exercise 7 (Week 8)- Debugging +

CSCI251/CSCI851 Advanced Programming

Laboratory Exercise 7 (Week 8)
Note that lab exercises marked with a * are effectively extension exercises.
1 Task One: Debugging +
1. There are two related pieces of debugging code, Debug-A.cpp and Debug-B.cpp. They are based on
exercises from
Joyce Farrell, Object Oriented Programming Using C++, 3rd Edition, Thomson Learning.
Fix both so Debug-A.cpp can populate Persons.txt based on user input, and Debug-B.cpp can
read data from Persons.txt and show their details and a count on the number of them. Notice that
reading and writing are at the level of Persons objects using the insertion and extraction operators.
2. Buggy inheritance: Fix Debug-C.cpp. The run of this program, with input as shown (Blob etc.),
should be:
Enter painting’s title Blob
Enter artist Degas
Enter painting’s title Blob
Enter artist Alice
Enter painting’s title Blob
Enter artist Bob
Enter painting’s title Blob
Enter artist Picasso
Blob by Degas value $25000
Blob by Alice value $400
Blob by Bob value $400
Blob by Picasso value $25000
3. Consider that we have a class X with prototypes for the manager functions as below. Let Y be an
abstract data type we have defined. Why can some of the manager functions be considered to be
providing implict casting? Make sure you identify which provide such casting as well as why.
X();
X(string);
X(int);
X(double, double);
X(Y);
~X();
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2 Task Two: Relationships
1. For each of the following lists of related classes, describe which relationship(s) seems the most
appropriate: association, aggregation, composition, inheritance (specialisation/generalisation), . . ..
Where a multiplicity makes sense, what values would likely be appropriate?
(a) Library, books.
(b) Insects, legs, wings.
(c) Pet shop, big dogs, little dogs.
(d) Insects, ants, spiders.
(e) Pencil case, pencils.
(f) Robots, androids, humans.
2. Consider that we intend to model apples, making use of at least two classes, Tree and Apple.
(a) Why might it make sense to have a private constructor for Apple that can only be accessed by
an instance of a class derived from Tree?
(b) Sketch code for the implied relationship.
3. The code fragment in Three.cpp contains three classes: Subject, Student and Date. Which of the
relationships illustrates which concepts? Add code to flesh out the example.
4. Consider A-Class.cpp.
(a) What concept does it illustrate?
(b) How are the classes related?
(c) What happens if one of the objects in main was deleted? How does this differ across those
objects?
(d) What happens if we add an additional company and add a contract between John and the new
company?
3 * Task Three: Some short tasks
1. You should have used the stream manipulator endl a lot.
(a) How do the stream manipulators flush and ends differ from endl?
(b) Devise a test to illustrate the difference between using no output stream modifier, using endl,
and using flush. Implement the test.
2. Can you have class X inheriting from class Y and class Y inheriting from class X at the same time?
Write code to test this.
c Luke McAven, SCIT-EIS-UOW, 2019.
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