Description
CH-230-A Assignment 10
Problem 10.1 Error messages produced by the compiler (1 point)
Language: C++
Download and use the files:
https://grader.eecs.jacobs-university.de/courses/320142/cpp/Critter.h
https://grader.eecs.jacobs-university.de/courses/320142/cpp/Critter.cpp
and
https://grader.eecs.jacobs-university.de/courses/320142/cpp/testcritter.cpp.
You will need to create a project to successfully compile all three files (or compile them from the
command line as specified on the slides).
a) Comment out the using namespace std; and then take your time, read and interpret
the error messages.
b) Also remove the Critter:: prefix in one of the methods in Critter.cpp, read and interpret the error message.
Then create a file called explanations.txt. This file should be uploaded together with the
other files and should contain your descriptions and interpretations of the errors as well as your
comments on potential alternative solutions.
You can assume that the input will be valid.
Problem 10.2 The Critter class (1 point)
Language: C++
Use the previously given files: Critter.h, Critter.cpp and testcritter.cpp.
Expand Critter.h by two additional properties of your choice, and corresponding setter and
getter methods, then adjust Critter.cpp and testcritter.cpp accordingly.
Also adapt the print() method such that the new properties are printed on the screen as well.
You can assume that the input will be valid.
Problem 10.3 A City class (1 point)
Language: C++
Create a class named City. Assume that a city has a name, a number of inhabitants, a mayor
and an area (in km2
).
Then create three instances of this class: Bremen, Paris and London. Provide suitable setter and
getter methods for each of these properties. The class declaration has to be placed into City.h,
the class definition has to be placed into City.cpp and the test program where the instances are
created has to be in testcity.cpp.
You can set the needed data from the main() function by initialization or read it from the keyboard.
Problem 10.4 Constructors for Critter (1 point)
Language: C++
Add three constructors to the class Critter. Each constructor should also print a simple informational message on the screen such that one can see when and which constructor has been
called.
You should be able to create an instance of the Critter class
(1) without supplying any properties (which should set the name to ”default_critter”, the
height to 5 and the rest to 0),
(2) by only supplying a name as parameter (which should set the height to 5 and the rest to 0),
and also
(3) by supplying name, hunger, boredom and height all as parameters. You should also be able
to create an instance of the Critter class without specifying the height. If the height is not
supplied, the critter has the default height of 10.
Write a test program which creates four instances of the Critter by using these three different
constructors (the last one in two ways). Set their hunger levels to 2 by using appropriate method
and/or constructor calls. The critters’ properties should then be printed on the screen.
Name the files Critter.h, Critter.cpp and testcritter.cpp.
Problem 10.5 Information hiding I (1 point)
Language: C++
A game developer crew has decided to rather use a percentage scale (double value between 0.0
and 1.0) to represent the hunger level of a critter. Change the internal structure of the class to reflect this. However, your existing test program should run without any modifications (therefore
the public class interface stays the same) and you will need to find a way to convert the current
hunger levels from integer values (which are from 0 to 10) to doubles and then from doubles
back to integers. Use separate methods for doing this.
Use a simple mapping scheme like 10 is 1.0, 9 is 0.9, 8 is 0.8 . . . 1 is 0.1, and 0 is 0.0.
Name the files Critter.h, Critter.cpp and testcritter.cpp (must remain unchanged).
The implementation for the conversions needs to be put into Critter.cpp and should not be
part of the public interface.
The client program testcritter.cpp from the previous problem must remain unchanged.
The hunger levels of the critters should be “internally” at 0.2 (meaning 20%).
You can assume that the setting values are always valid.
Problem 10.6 Information hiding II (1 point)
Language: C++
Next a thirst level (as double value) should be added to the properties of a critter. Add a new
constructor that takes five parameters for setting all properties of a critter.
Make also sure that the existing constructors will still work. For the existing constructors, the
thirst level should be set to the same level as the hunger level.
Your existing testcritter.cpp
must still be able to run in its unchanged form. So the already existing constructors need to
support the change. Name the files Critter.h, Critter.cpp and testcritter.cpp.
Finally, you should adapt the print method for printing on the screen also the value of the thirst
level as a double. The client program testcritter.cpp may contain one additional line, where
the constructor taking five parameters is being called.
You can assume that the setting values are always valid.
Problem 10.7 Copy constructor (1 point)
Language: C++
Download the file:
https://grader.eecs.jacobs-university.de/courses/320142/
cpp/copyconstructor.cpp
Based on the source code of copyconstructor.cpp implement the method funcByref().
Change all constructors (including the copy constructor) such that you can clearly see when and
which of them is invoked by adding a message which is printed on the screen.
Then in your main() function create at least two objects using the different constructors, call
funcByVal(), funcByRef(), and print the results on the screen. Then make sure that the
memory occupied by the objects will be released by the end of the program.
You can assume that the setting values are always valid.
Problem 10.8 A Complex class (2 points)
Language: C++
Create a class named Complex for storing and managing complex numbers. A complex number
has an real part and an imaginary part. The class has to provide a default constructor initializing
the properties by 0, another constructor for setting the properties with specific values, a copy
constructor and an empty destructor.
Provide suitable setter and getter methods for each property and a method for printing the complex number on the screen in its mathematical form (e.g.,
1 + 2i, 3 − 5i). Also provide methods for the conjugation of a complex number, and for adding,
subtracting and multiplying two complex numbers. The class declaration has to be placed into
Complex.h, the class definition has to be placed into Complex.cpp and the test program where
the instances are created has to be in testcomplex.cpp. The test program should create at least
two instances of the Complex class, the data for the properties should be read from the keyboard.
Then:
a) the conjugate of the first instance should be determined and printed on the screen;
b) the sum of the two instances should be determined and printed on the screen;
c) the difference between the second and first instance should be determined and printed on
the screen;
d) the multiplication of the two instances should be determined and printed on the screen.
The prototypes of the methods for adding, subtracting and multiplying must have the following
form:
Complex Complex::add(Complex);
Then the usage will be the following:
Complex c1, c2, c3;
…
c3 = c1.add(c2);
Note: If z = a + bi then z = a − bi. If z1 = a + bi and z2 = c + di then z1 + z2 = (a + c) + (b + d)i,
z1 − z2 = (a − c) + (b − d)i and z1 · z2 = (a · c − b · d) + (b · c + a · d)i.
You can assume that the input will be valid.
How to submit your solutions
• Your source code should be properly indented and compile with gcc or g++ depending on the problem without any errors or warnings (You can use gcc -Wall -o program program.c or g++
-Wall -o program program.cpp). Insert suitable comments (not on every line . . . ) to explain
what your program does.
• Please name the programs according to the suggested filenames (they should match the description
of the problem) in Grader. Otherwise you might have problems with the inclusion of header files.
Each program must include a comment on the top like the following:
/*
a10 p1.[c or cpp or h]
Firstname Lastname
myemail@jacobs-university.de
*/
• You have to submit your solutions via Grader at
https://cantaloupe.eecs.jacobs-university.de.
If there are problems (but only then) you can submit the programs by sending mail to
k.lipskoch@jacobs-university.de with a subject line that begins with CH-230-A.
It is important that you do begin your subject with the coursenumber, otherwise I might have
problems to identify your submission.
• Please note, that after the deadline it will not be possible to submit any solutions. It is useless to send
late solutions by mail, because they will not be accepted.
This assignment is due by Monday, November 15th, 23:00.
