Computer Programming Concepts and Visual Basic David I. Schneider

370 Computer Programming Concepts and Visual Basic
For instance, consider the situation of Example 1. If we are using social security number
as a key, and the object pupil contains the data for Brittany Brown, then the statement
section.Add pupil, “222-33-4444”
would assign the string “222-33-4444” as a key for her data. Then her name property can
be accessed with
section.Item(“222-33-4444”).Name
EXAMPLE 2
Extend the program of Example 1 so that the grade for an individual student can be displayed by giving
a social security number.
SOLUTION:
There are no changes in the two classes. In the Sub cmdAdd_Click procedure of the form code, change
the line
section.Add pupil
to
section.Add pupil, txtSSN.Text
Place an additional command button (cmdDisplay) with the caption “Display Single Grade” on the form
and add the following event procedure for this button:
Private Sub cmdDisplay_Click()
Dim ssn As String
ssn = InputBox(“Enter the student’s social security number.”)
picGrades.Cls
picGrades.Print section.Item(ssn).Name; _
Tab(28); section.Item(ssn).SocSecNum(); _
Tab(48); section.Item(ssn).SemGrade
End Sub
When this command button is pressed, the input box in Figure 12-1 appears. To obtain the output in Figure
12-2, run the program, enter the same data as in the execution of Example 1, press the “Display Single
Grade” button, type 222-33-4444 into the input box, and press Enter.
FIGURE 12-1 Input Box FIGURE 12-2 Output of Program