Introduction
In this project (and the
labs accompanying it) you will write a series of programs [applications] that
look up and display astrological signs and dates. The programs that will make
up the project are as follows:
This Time – a digital clock with the
date on the window bar
Sign Finder – present your birthday and
be told your astrological sign
Day Finder – generalizing the Sign
Finder to ask a series of questions to find the respondent's birthday using
binary search
Two of these applications
will be done in lab:
This Time (Lab 7) and Sign Finder (Lab
9)
Those two applications will
help you prepare the two parts that will be turned in for Project 2:
The various projects are written in Visual Basic 6.0 and serve as your introduction to algorithmic thinking, program design and the characteristics of VB6.
It is suggested you create a new folder for each project piece of the assignment. This will assist you in keeping track of all of the various files produced as well as simplify the saving of your work to Dante or a floppy disk.
This Time: This is a simple digital
clock program with the date on the window bar. The interface (GUI) that you
will create has the following form and the solution will be covered in Lab 7.
Sign Finder: The Sign Finder
program will be discussed briefly in class and you will go through the solution
in Lab 9. Sign Finder has the following graphic interface (adjust colors and
font styles any way you wish to):
Part 1:
The objectives of this project piece are:
· Create your first VB application
· Develop experience with form creation and refinement
· Understand how an algorithm is expressed in a programming language
· Understand the flow of information through variables
· Understand the concept of “event programming”
· Practice using the Visual Basic IDE and managing project development.
The application will present
the user with a set of 12 radio buttons corresponding to the Zodiac signs, and
when one radio button is pressed, followed by a click of OK, will print out the
starting and ending dates of that sign. The main task is to construct the form
to have the 12 radio buttons, one command button and five labels.
The next window results from clicking "Leo" and
"OK"
The overall logic is as
follows. The form contains all of the structures shown in both displays above.
For the initial display, the "You were born" text, the dates
and the "and" text are all hidden. When the command (OK)
button is pushed, the command button is hidden, and the "You were
born" text, the Go Again button, etc. is made visible.
Detailed Steps of What to Do:
(a) Create
a new project and a form template. Name
the Project Zodiac
(b) Rename
the form object frmZodiac
(c) Save
the form and the project, maintaining “frmZodiac” as
the form name
and "Zodiac" as the project name. The ".frm" and ".vbp" extensions are added automatically.
(d) Select a new background color and make other changes to the form you think are appropriate to make it attractive and appealing.
(e) Double
click on the form to bring up the code window.
(f) Add
the terms Option Explicit line at the top of the code
window if Option Explicit is not shown
(g) Enter
the following variable declarations: (see next page)
Dim loMonth As String
Dim hiMonth As String
Dim loDay As Integer
Dim hiDay As Integer
Notice how VB’s “word completion” tries to assist after the "As" is entered. The two
string variables will represent the two months that the astrological sign
spans, and the two integer variables will represent the starting and ending
days. So, for Leo, the loMonth will be assigned the value
"July " and hiMonth will be assigned "August ". The loDay variable will be assigned 23 and the hiDay will be assigned 22.
Aries
|
March 21
|
April 19 |
||
|
Taurus |
April 20 |
May 20 |
||
|
Gemini |
May 21 |
June 20 |
||
|
Cancer |
June 21 |
July 22 |
||
|
Leo |
July 23 |
August 22 |
||
|
Virgo |
August 23 |
September 22 |
||
|
Libra |
September
23 |
October 22 |
||
|
Scorpio |
October 23 |
November 21 |
||
|
Sagittarius |
November
22 |
December 21 |
||
|
Capricorn |
December
22 |
January 19 |
||
Aquarius |
January 20 |
February 18 |
||
|
Table 1:
List of Astrological Signs |
February
19 |
March 20 |
(h) In
the form, place the 12 option or radio buttons, naming each with a
new name. The name should begin
with the letters "opt" (stands for option button) and
be followed by the first three letters of the sign. The name for the Aries
button will be optAri. Change the caption on the
button to the intended Zodiac sign. Change the background color, font and any
other features of the button that you need to make it aesthetically pleasing.
(i)
Once the buttons are defined, place
labels for the text lines on the form:
"Enter
your Zodiac sign"
"You
were born between"
"starting date"
"and"
"ending date"
Name the labels lblEnter, lblBorn, lblStDate, lblAnd, lblEndDate, respectively. Change the
fonts, background colors and any other needed properties. The last four labels
should be hidden, i.e. have their visibility property
set to "false".
(j) Click on each radio button to bring up the code window with the
"click event" handler for that button. Customize it by setting the loMonth to the starting month
(followed by a space) in quotes, hiMonth to the ending month
(followed by a space) in quotes, loDay to the starting day for the
sign, and hiDay for the ending day for the
sign. The extra space is included so the day doesn’t smash into the month when
printed out. For example, the Capricorn "click event" handler would
be:
Private Sub optCap_Click()
loMonth = "December "
hiMonth = "January "
loDay = 22
hiDay = 19
End Sub
There is one further trick
that can be used to make the text appear more natural when it is printed.
Assume that the start date precedes the " and ", which is
followed by the end date. If these are all printed on the same line, and the
start date is right justified, then the two dates will "hug" the
"and" and make the text appear without spaces.
(k) Add a command button, renamed cmdOK and captioned OK. Modify its visual
properties appropriately. Click on the OK command button to bring up the code
window with the cmdOK_Click procedure. Set the start and
end dates by changing the captions as follows:
lblStDate.Caption = loMonth & loDay
lblEndDate.Caption = hiMonth & hiDay
Further, set the visibility
of the lblBorn, lblStDate, lblAnd,
lblEndDate, to True, and visibility of cmdOK to be False.
(j) Finally, add one last command button,
rename it cmdGoAgain and
make
the caption Go Again. Click on the Go Again
command button to bring up the code window with the cmdGoAgain_Click procedure. Use this event to reset your form so that
a user may play more than once. Use what
you know about properties of objects from your previous steps and think about
the statements you must include in this event in order to clear the form and
bring the OK button back.
The program should now run. Save it. Compile it. Try it out. Show it to your friends, your parents, your dog and notice their utter amazement that a computer could be made to do such an amazing feat, a skill once reserved only for astrologers!
Grading Criteria for Zodiac
Range
The Zodiac Range program
will be graded on the following criteria:
- Structure and organization of the form, including how attractive the layout is.
- Operation of the Application – does it work?
- Completeness – finishing all aspects of the work
Part I is due on October 31st by
Your hard copy (turned in by
Your name
Student ID
Lab Section
Your form code
A screen capture of the form
Part II: Day Finder Due November 7th by
The Day Finder is a
small extension to the Zodiac program but very significant because it
introduces a powerful algorithm, binary search.
Searching for a day. The Day Finder is an extension of the Zodiac
application in which the user is asked questions that enable the program to say
what day he or she was born on.
Leos are known by the Zodiac
application to be born between July 23 and August 22. (Remember this includes
both the starting and ending dates.) The task is to ask the user questions to
determine which day is the user’s birthday. One strategy would be to ask,
"Were you born after July 23?" If the answer is "no", then
the program can say, "You were born on July 23", but if the answer is
"yes", the program has to try another question, like "Were you
born after July 24?"
If the person is born on
August 22, this strategy would take 30 questions to cover the 9 days in July
(23-31) and the 22 days in August (1-22), which is actually 31 days, but we
don’t have to ask about the last day, since a "no" to "Were you
born after August 21" implies an August 21 birthday, while a
"yes" implies an August 22 birthday.
There is a better way than
the one mentioned above. The Day Finder will use an intelligent
searching strategy, called the binary search algorithm. Binary search
can be used on any ordered objects, like letters or the dates of a Zodiac sign.
It uses a series of questions, sometimes called probes, to eliminate
half of the remaining possibilities with each question.
For example, suppose I’m
thinking of a letter. You may ask, "Is the letter between N and Z?", a question that is equivalent to asking if it is in
the last half of the alphabet (“Is it AFTER M?”).
Regardless of which answer
is given, half of the alphabet is eliminated. The binary search for the letter
"L" goes as follows: (see next page)
Question Is the letter after M? Is the letter after G? Is the letter after J? Is the letter after L? Is the letter after K? The letter must be L Answer No Yes Yes No Yes Letters Removed A B C D E F G H I J K L M Notice two points about the
example: First, the questions always ask
if the letter is after the probe letter. It is possible to ask before
and after questions, but always asking the same type simplifies the
algorithm. Second, the intervals sometimes
have an odd number of letters and sometimes an even number. When it is an odd
number, then the middle letter is the probe. When it is an even number, e.g.
A-Z, then the probe is the last element of the first half of the interval. This
is because of the "after formulation" of the questions. If the
questions had been formulated as before questions, then the first
element in the second half should be used. By the way, it takes only five questions to
find any letter using binary search on the alphabet. Finding a birthday works in
the just the same way. The only complication is that the sequence of days
changes months under the sign, e.g. Leo goes from July to August. This is not
really a problem, however, if we change slightly how we think about the
dates. Imagine that the month didn’t
change - then we would look for the birthday from July 23rd through
July 53rd. Of course, there is no July 53; that’s what August 22
would be if the month didn’t change. July August Leo
Leo
as extended July Dates The 53 is how far past the
end of July the Leo sign goes, which is computed by adding the number of days
in July, 31, to the last day of the sign, the 22nd, giving 31 + 22 =
53. This means that the search can look for the birthday between 23 and 53, and
whenever a question must be asked about a date larger than 31, the day gets 31
subtracted from it and the month becomes August. Otherwise it is just a normal
July date. For example, to figure out
the first question to ask, we find the midway point between July 23 and July 53
by subtracting the smaller endpoint from the larger: 53 – 23 = 30 and dividing by 2 30 \ 2 = 15 If the number had been odd,
the 0.5 would have been truncated (or rounded down). Then this number is added
to the start of the Leo sign, the 23rd 23 + 15 = 38 which is a day in August since it
is larger than the largest day in July, the 31st. Thus, July 38 is
really August 7th, since 38-31 = 7 (see diagram above). And, it can
be checked that this is the middle of the Leo range, just by counting out the
days. The result of this computation would be to ask the question: To us, the programmers, this
is July 38. If the answer is "no," then the new interval is 23 to 38.
Remember, August 7 (= July 38) is still a possibility. If the answer is
"yes" then the interval is 39 to 53. By repeatedly shrinking the
interval we can reduce the interval size to one day, say 32 to 32. And that
must be the person’s birthday. The questions to find the
birthday August 1 are as follows, where Lo is the lower end of the interval, Hi
is the upper end of the interval, Mid is the computed midpoint and Size is the
size of the interval. Notice that when the
endpoints are the same, then they must be for the birthday being sought. Form window asking the first question for the Day Finder application. The objectives of this part
of the project are: The Day Finder will be an
extension of the Zodiac program. The
first step is to make a copy of the Zodiac form. Use Save As in the File menu. This new form
will include the features needed to implement a Yes/No dialog that generates
probes to find the user’s birthday. To begin this next part of Project 2, add
four more variables to the integer declarations at the start of your program: Dim hiMonth As String Dim loDay As Integer Dim hiDay As Integer Dim loEnd As Integer New variable Dim hiEnd As Integer New variable Dim midPt As Integer New variable Dim numDays As Integer New variable Once the declarations are
in, each of the
twelve Zodiac option event handlers must be added to. In each option click event the variable numDays
must be assigned
the number of days in the loMonth month. This tells the program
on what day the month changes. For example, for Leo July is the loMonth, which has 31 days, so numDays
= 31 must be
added to Leo. The 2 variables, loEnd and hiEnd will hold the end values of
the interval being searched. MidPt will be used to represent
the probe point in the center of the interval and numDays will be the number of days of the month in which the sign
begins. This value will be used as to
implement the Extended Month Technique. The Day Finder follows the
work of the Zodiac program. The program
then asks a series of questions that implement a binary search over the range
set by Notice that except for form modifications (the aesthetics
of display) and variable declarations, the steps can all be associated with one
or more events, shown in brackets. This
is a feature of Event Based Programming – the whole process is arranged so that
when an event like a button click happens, the program takes the proper
actions. Thinking of what that action
should be is an easy way to understand the logic. The following discussion goes into each of the 5 steps in the Overall
Logic. a) Additional Variable Specifications The click event handler for each
sign’s radio button, which already contains assignment statements for loMonth, hiMonth, loDay
and hiDay, must have an
assignment to numDays, the
last day of the month given by loMonth. For example, for the Leo event handler, the loMonth is “July ”, and the last day of July is the 31st. So, numDays = 31 should be
included in the Leo event handler. The
purpose of keeping track of the last day of the month is so that the lower
month can be “extended” as explained above. b) Form
modifications The form for the Day Finder adds
to the same code used in c) Search setup Once the form’s visibility has
been set, the binary search must be set up and the first question asked. The range will be bounded by loEnd and hiEnd, which should
be assigned values based on loDay, hiDay and numDays for each sign and the Extended Month
Technique. Once the interval is
initialized, the first question is asked. d) Compute the probe (the midpoint) Questions will be asked in
OK (the first question) and Yes and No events.
To find the probe requires the midPt to be calculated as noted above. It is important to re-emphasize that when
dividing by 2 to compute the midPt, the integer division
symbol (\) should be used rather than the normal division symbol (/). Why? Because with the normal division symbol the results may include
decimals. Nobody notes their
birth date on half a day, or .3 of a day, so we use the integer division symbol
to make sure the result is always a whole number. e) Printing out the guess questions The guess must be printed as
“Were you born after ” month day ? The midPt value, which ranges over the Extended Month, can be used to
determine the proper values for month and day. If midPt is less than or equal to numDays, then the month is the lower month (loMonth), otherwise it is
the higher month. Also, if midPt is less than numDays, then midPt is the proper
value for day. Otherwise, by the
Extended Month Technique, midPt is too large by the amount of numDays, which must be
subtracted off to get the right day value (and the month will be
the higher month). To hook together the month
word and the day number to form the guess to be displayed, use the concatenate
operation (&) which is used to put two letter strings together. (The number will be converted to a letter
string.) Assigning the result to the
caption property of the label control used for guessing (introduced in (b)
above), prints out the guess and waits for the user to respond by clicking Yes
or No. f) Reducing the interval by half When the user clicks Yes or
No, he or she has given birthday information and the interval must be reduced
before the next question is asked. Since
the questions are “after” questions, a Y reply means
that the lower half of the interval can be discarded. So, the loEnd should be moved up
to just beyond the midPt, i.e midPt + 1. IF the reply is N, then the upper part of the
interval is to be discarded, and hiEnd should be moved down to midPt. g) Recognizing the birth date (termination of the binary
search) Any binary search ends when
the interval has a size of 1, since that must be the item we are looking
for. At that point
the label “Your birthday is ” should replace the “Were
you born after “ label, and the day printed out. h) Explain how it works Finally, write a paragraph
explaining how the binary search works.
Write it as though you were explaining it to a friend who has not yet
learned any programming, but with enough detail that he/she understands the
entire process. Include discussion of
the main ideas of the algorithm and how it has been converted into the specific
program for finding a birthday given the Zodiac sign. The Day Finder program will
be graded according to the following criteria: Part II is due on November
7th by Your electronic submission
will include 3 files: one with a .vbp extension (e.g. DayFinder.vbp),
another with a .frm
extension (e.g. frmDayFinder.frm) and a third with a .exe
extension (e.g. DayFinder.exe). If you
have added any images to your form and you want us to be able to see them, the
executable is absolutely essential. Your hard copy (turned in by
Your name Student ID Lab Section Your write-up Your form code A screen capture of the form
N O P Q R S T U V W X Y ZA B C D E F G H I J K L M N O P Q R S T U V W X Y ZA B C D E F G H I J K L M N O P Q R S T U V W X Y ZA B C D E F G H I J K L M N O P Q R S T U V W
X Y ZA B C D E F G H I J K L M N O P Q R S T U V W
X Y Z
Were you born after August 7?
Dim loMonth As String
Overall Logic
Detailed Logic
Grading Criteria for Day Finder