Computer Programming Concepts and Visual Basic David I. Schneider

232 Computer Programming Concepts and Visual Basic
TABLE 7.2
Tasks and Their Procedures
Task Procedure
1. Set up data file and form Form_Load
1.1 Create data file CreateDataFile
1.2 Read data file ReadDataFile
1.3 Set up check SetupCheck
1.4 Initialize text fields InitializeFields
2. Record check or deposit slip cmdRecord_Click
2.1 Verify that required data are given AllDataGiven
2.2 Initialize text fields InitializeFields
3. Toggle between check & deposit slip cmdMode_Click
3.1 Set up check SetupCheck
3.2 Set up deposit slip SetupDeposit
3.3 Initialize text fields InitializeFields
4. Print summary of transaction cmdPrint_Click
5. Quit cmdQuit_Click
Let’s examine each event procedure.
1. Form_Load first looks to see if the file CHKBOOK.TXT has been created.
The function Dir returns “CHKBOOK.TXT” if the file exists and otherwise
returns the empty string. If CHKBOOK.TXT does not exist, the routine CreateDataFile
is called. CreateDataFile prompts the user for the name to appear
on the checks and deposit slips, the starting balance, and the numbers of the
first check and deposit slip, and then writes these items to the data file. If CHK-
BOOK.TXT does exist, the routine ReadDataFile is called to read through the
entire file to determine all information needed to proceed. The event procedure
calls SetupCheck to set the transaction type to Check and set the appropriate
captions and background colors for a check. The event procedure then calls InitializeFields,
which initializes all the text boxes.
In the first assignment statement of the procedure, the drive is specified as the
A drive. Therefore, the data file will be written to and read from a diskette on
the A drive. Feel free to change the letter A to whatever drive you prefer. You
may even want to specify an entire path.
2. cmdRecord_Click first confirms that the required fields contain entries. This
is accomplished by calling the function AllDataGiven. If the value returned is
True, then cmdRecord_Click opens the data file for output as Append, sends
eight pieces of data to the file, and then closes the file. When AllDataGiven
returns False, the function itself pops up a message box to tell the user where
information is needed. The user must type in the information and then press the
Record button again.
3. cmdMode_Click toggles back and forth from a check to a deposit slip. It calls
SetupCheck, or its analog SetupDeposit, and then calls InitializeFields.
4. cmdPrint_Click prints out a complete history of all transactions, as shown in
Figure 7-6.
5. cmdQuit_Click ends the program.
Dim fileName As String ‘Name of data file
Dim nameOnChk As String ‘Name to appear on checks
Dim lastCkNum As Integer ‘Number of last check written
Dim lastDpNum As Integer ‘Number of last deposit slip processed
Dim curBal As Single ‘Current balance in account
Dim transType As String ‘Type of transaction, check or deposit
Private Function AllDataGiven() As Boolean