4003CEM-inheritance

lab_animal1

What happens if we add the following line of code to the end of the main function in lab_animal1.cpp?

a1.wander();

lab_animal2

Add the following line of code to the end of lab_animal2.cpp.

a1.wander();

What happens when we run the code now?

lab_animal3a

Open lab_animal3.h which to start with includes the two class definitions from lab_animal2.h. Underneath, add a third class definition, for a class called Bird. All instances of Bird should have an attribute canFly which is a Boolean and access to a method flap. The flap method should print a message containing the word flying only if the object in question has attribute canFly equal to true.

This will mean creating an appropriate Bird constructor as well. In order to pass the tests make sure that it expects the arguments in the following order name, colour and "can fly".

lab_animal3b

Add a line of code to the end of your solution in lab_animal3.cpp which assigns to a variable myBird an object of the Bird class which can fly, has name "Tweety" and is coloured "Yellow".

Get myBird to wander.

lab_animal4

Add a display() method to Bird. As with Dog the behaviour of the method should change depending on the attribute values for the object. If the Bird can fly it should state that it is a flying bird. If the Bird cannot fly it should state that is is a flightless bird.

lab_animal5

The display() method approach that we have used here is simple but not good approach for real code. We already have a method for printing things in C++, std::cout. If makes a lot of sense for us to get our classes to work properly with cout because if we do we automatically get compatibility with several other c++ features.

Copy your code from lab_animal4.h into lab_animal5.h. Replace the display() methods with friend methods that overload the << operator as discussed in the lecture.

lab_date and lab_time

Open the files lab_date.h and lab_time.h.

• lab_date.h defines a class Date: -- Every instance has three attributes: day, month, year.
  -- There is a method forward which moves the object's date on by one day (updating months and year accordingly).
  -- It uses a class attribute monthDays of the number of days in each month.

• lab_time.h defines a class Time: -- Every instance has two attributes: hr and min.
  -- There is a method tick which moves the object's time on by one minute (updating hour accordingly).

Both classes also have simple constructor and display methods.

Experiment with the classes and try out the methods.

lab_datetime

Fix the leap year and other rollover bugs in the DateTime class.

• You should already have the correct leap year logic from the previous weeks.
• How would you go about testing the 3 parts of the DateTime class? (i.e. Date, Time and DateTime).Remember to ask the lab staff any questions you have - don't be shy - we are here to help!

lab_database

In the file lab_database.h write code to implement a basic database of people in a university according to the class Hierarchy Diagram shown in Images/database file.

Of course, in reality there are far more sophisticated tools for making databases - this is just an exercise in class design.

Remember, in each box:

• The top part is the class name.
• The middle part are the attributes (all object attributes here).
• The bottom part are the methods.

The arrows show the inheritance relationships. So Staff should be an extension of Person for example.

• Each constructor should take a name parameter.
  • With the exception of the PhdStudent, who should also take a parameter of type Academic to use as the supervisor.
  • This is a more challenging class so maybe work on that one last.
• classesTeaching and modules should be initialised as empty vectors.
• id should be initalised as a random number.
• feesPaid should be initialised as false.

All other attributes are initialised as empty strings. The setters should require appropriate parameters.

You can of course extend your code as you wish.