Lab 8

Lab 8.0 – Coordinated Files

Goals:

w Use an array of arrays

w Learn use of the Menu control

w Use multiple data files

X Create a “master file”

X Manage data in various files

__1. Set up the basic file components for creating the data base.

w Create files for starting up the data base

X Using Notepad, create a file, advlist, with these contents

Bruce

Bumblebee

file1

Sally

Strudel

file2

X And a file, file1, with these contents

Jerry

Reinsdorf

Alice

Appleby

Keisha

Kramer

Mike

Tyler

Ahmad

Rashad

X Plus a file, file2, with these contents

Ron

Jaworksi

Donovan

McNabb

Melissa

Meyers

Chamique

Holdsclaw

Jean

Kirkpatrick

__2. Create an array of simple data base records.

w Start up a new VB project, prjSched, with one form, frmSched.

w Add a module to the project for global data structures.

X From the menu bar choose Project, then click on Add Module.

X Click on New.

X Rename the module mdlDataStruc.

w Within that module set up the data structures below

Public Type crsTaken

course As String * 6

section As String * 3

days As String * 3

time As String * 15

End Type

Public Type stuSched

firstname As String * 12

lastname As String * 12

major As String * 20

courses(1 To 7) As crsTaken

End Type

Public onestudent As stuSched

Public student(1 To 5) As stuSched

Public Type advisorType

firstname As String * 12

lastname As String * 12

End Type

Public advisor(1 To 2) As advisorType

Public advnum As Integer

Public stunum As Integer

Public crsnum As Integer

Public stufileopen As Boolean

w How does this declaration differ from declarations we have done

previously? Why the differences?

__3. Begin to learn about the Menu control.

w Enter the Menu Editor

X Bring the form to the forefront, if it is not already there

X Move the cursor along the toolbar to the 3rd icon from the left.

As you wait, the words Menu Editor should appear.

X Click on that icon.

w Create the skeleton of a drop down menu.

X In the Caption: textbox type Main

X In the Name: textbox type mnuMain

X Click on OK

w We now have the rudiments of a menu

X Notice the word Main in the upper left corner of the form

X Click on it. The code window opens.

We could write code at this point, but we will not do so.

Instead we will be giving it some submenu items.

__4. Create submenu items for mnuMain.

w Enter the Menu Editor again

w Check online Help for information

X When the Menu Editor window opens, press F1

X Peruse the information there, noticing especially the

description of the Right, Left, Up and Down Arrows.

w Create the first submenu item

X In the largest window at the bottom of the Menu Editor form,

position the cursor just below the word Main and click.

X Type Create Files and mnuCreate for the caption and name

X Click on the Right Arrow to make it a submenu item to Main.

X Click on the scroll arrow for Shortcut: and choose Ctrl+C

from the items presented.

X Open the code window for that submenu item and type:

Debug.Print “OK”

X Test your code. Does it work?

w Create two more submenu items

X Create submenu item named Load Files and give it a

shortcut of Ctrl+L.

X Do not give it any code

X Create submenu item named Exit and give it a

shortcut of Ctrl+E.

X Give it this code

End

w Run your program and test the Exit submenu item.

__5. Create a framework for working with a data base of student schedules.

w Add a frame control to the form.

w Place on that frame textboxes for displaying one student schedule.

w Add two listboxes to that frame

X One for listing advisee courses

X A second one for listing advisees

w Add a listbox to the form, but outside the frame for listing advisor w Write code to position and size the above items achieving an effect

similar to the one below.

__6. Now write code for creating the student files.

w Open the code window for Create stuFiles.

w Delete the old code.

w Replace it with this code.

Open App.Path & "\advlist.txt" For Input As #1

Open App.Path & "\advisors" For Output As #2

Close #2

Call AddOneAdvisor(1)

Call AddOneAdvisor(2)

Close #1

X Why do we open the advisors file, then close it right away?

w Now add the code for AddOneAdvisor

Public Sub AddOneAdvisor(ByVal advn As Integer)

Dim first As String

Dim last As String

Dim filename As String

Line Input #1, first

Line Input #1, last

Line Input #1, filename

lbxAdvisors.AddItem Trim(first) & " " & Trim(last)

Open App.Path & "\advisors" For Append As #2

Print #2, first

Print #2, last

Close #2

advisor(advn).firstname = first

advisor(advn).lastname = last

Call CreateStudentsFile(last, filename)

End Sub

X Why are we using Line Input #?

X What is the purpose of Trim?

X What does the variable filename refer to?

X What happens when a file is opened For Append?

X Why do we choose that particular file opening mode here?

w Part of the code for CreateStudentsFile is below. Complete it and

add it to the program.

Public Sub CreateStudentsFile(ByVal lname As . . ., ByVal fname As . . .)

Dim . . .

Dim crs As Integer

Open . . . & "\" & fname & ".txt" For . . . As #2

Open . . . & Trim(lname) & "-stu" For . . . As #3 Len = . . .

For i = . . .

Line Input #2, . . .

onestudent.major = "Computer Science"

For crs = 1 To 7

onestudent.courses(crs).course = "none"

Next crs

Put . . .

Next i

Close . . .

End Sub

w Let’s think for a minute about what we’ve done.

X Our goal was to produce a file with a list of advisors.

And for each advisor we created a file with a list of advisees,

tied by name to the advisor.

X We started with the file advlist. Was it necessary to start that

way? Could we have input the advisor information at run time

from a textbox? If not, why not? If so, how?

__7. Create code for accessing the advisor file we created.

w For the Load Files menu item, complete the code below.

Dim i As Integer

lbxAdvisors.Clear

Open App.Path & "\advisors" For . . . As #1

For i = 1 To 2

Input #1, . . .

lbxAdvisors.AddItem advisor(i).firstname & " " & advisor(i).lastname

Next I

Close #1

X What does the Clear method accomplish?

X Why do we use it here?

X Why is it important for us to close the file at the end of this

procedure?

__8. Write code for accessing the advisee files we created.

w Add to Form_Load this line of code.

stufileopen = False

w For the click event of lbxAdvisors, complete the code below.

Dim stu As Integer

advnum = lbxAdvisors.ListIndex + . . .

If stufileopen Then Close #9

Open . . . & "\" & Trim(advisor(advnum).lastname) & "-stu" For . . . As #9 Len = . . .

stufileopen = . . .

lbxStudents.Clear

For stu = 1 To 5

Get #9, stu, onestudent

lbxStudents.AddItem . . .

Next stu

X What is the purpose of the Boolean variable stufileopen?

X Why do we check its value and take the action taken?

w Now write code for the click event of lbxStudents.

X The code should fill in the 3 textboxes and the courses listbox

that are on the frame.

X Remember that the appropriate student file is still open.

X Give the global variable stunum its proper value. We’ll need

that later for saving changes made.

__9. Finally we will produce an interface for supplying course information.

w Add form frmCourse to the project.

w Give it textboxes for displaying information about each course.

w Give it two command buttons labeled UPDATE and OK.

X Give the OK button this code.

Me.Hide

frmSched.Show

X We will write code for the UPDATE button later.

w Write code for the click event on lbxCourses to do the following:

X Set the global variable crsnum to the course clicked on.

X Make form frmSched disappear.

X Make form frmCourse appear.

X What code did you write?

w Now write code for the Form_Activate event of frmSched.

X Fill in the textboxes of frmSched.

X Remember that global structure onestudent contains the

complete record of the chosen student and global variable

crsnum contains the index of the course clicked on.

w Now write code for the UPDATE button of frmSched.

X The button does not save to long term storage (i.e., the disk)

but only to short term storage (i.e., the current student record).

X Remember, again, the global values at your disposal.

X What code did you write?

w And now add another menu item for saving to disk any changes

made to the current student data displayed.

X What code did you write?

__10. Run your program. Test it thoroughly.

__11. You may have noticed that after clicking UPDATE any change to the course id does not appear in lbxCourses of frmSched, although choosing Save from the menu does make the change permanent. To make that change is not quite a straightforward matter.

w Extra: Write code to make this happen.