Computer Programming Concepts and Visual Basic David I. Schneider

462 Computer Programming Concepts and Visual Basic
3. Press F8 two more times. The Call statement is highlighted.
4. Press F8 once and observe that the heading of the Sub procedure GetBalance is
now highlighted in yellow.
5. Press F8 three times to execute the assignment statements and to highlight the
End Sub statement. (Notice that the Dim and Rem statements were skipped.)
6. Press F8 and notice that the yellow highlight has moved back to the cmdButton_Click
event procedure and is on the statement immediately following the
Call statement.
7. Click on the End icon to end the program.
8. Repeat Steps 2 and 3, and then press Shift+F8 to step over the procedure Get-
Balance. The procedure has been executed in its entirety.
9. Click on the End icon to end the program.
COMMUNICATION BETWEEN ARGUMENTS AND PARAMETERS
The following walkthrough uses the Locals window to monitor the values of arguments and
parameters during the execution of a program.
1. If you have not already done so, type the preceding program into the Code window.
2. Press F8 and click on the command button.
3. Select “Locals Window” from the View window. Notice that the variables from
the cmdButton_Click event procedure appear in the Locals window.
4. Press F8 three more times to highlight the Call statement. Notice that the value
of the variable p has changed.
5. Press F8 to call the Sub procedure. Notice that the variables displayed in the
Locals window are now those of the procedure GetBalance.
6. Press F8 three times to execute the procedure.
7. Press F8 to return to cmdButton_Click event procedure. Notice that the value
of the variable b has inherited the value of the variable bal.
8. Click on the End icon to end the program.
STEPPING THROUGH PROGRAMS CONTAINING SELECTION
STRUCTURES: SECTION 4
If Blocks
The following walkthrough demonstrates how an If statement evaluates a condition to determine
whether to take an action.
1. Create a form with a command button (cmdButton) and a picture box (picBox).
Set the AutoRedraw property of the picture box to True. Then open the Code
window and enter the following procedure:
Private Sub cmdButton_Click()
Dim wage As Single
picBox.Cls
wage = Val(InputBox(“wage:”))
If wage < 5.15 Then
picBox.Print “Below minimum wage.”
Else
picBox.Print “Wage Ok.”
End If
End Sub