Computer Programming Concepts and Visual Basic David I. Schneider

78 Computer Programming Concepts and Visual Basic
FIGURE 3-1 Passing Arguments to Parameters
This feature allows values obtained as input from the user to be passed to a Sub procedure.
EXAMPLE 5
The following variation of the addition program requests the two numbers as input from the user. Notice
that the names of the arguments, x and y, are different from the names of the parameters. The names of
the arguments and parameters may be the same or different; what matters is that the order, number, and
types of the arguments and parameters match.
Private Sub cmdCompute_Click()
Dim x As Single,, y As Single
‘This program requests two numbers and
‘displays the two numbers and their sum.
x = Val(txtFirstNum.Text)
y = Val(txtSecondNum.Text)
Call Add(x,, y)
End Sub
Object Property Setting
frmAdd Caption Add Two Numbers
lblFirstNum Caption First Number
txtFirstNum Text (blank)
lblSecondNum Caption Second Number
txtSecondNum Text (blank)
cmdCompute Caption Compute Sum
picResult
Private Sub Add(num1 As Single,, num2 As Single)
‘Display numbers and their sum
picResult.Cls
picResult.Print “The sum of”; num1; “and”; num2; “is”; num1 + num2
End Sub
[Run, type 23 and 67 into the text boxes, and then click the command button.]
EXAMPLE 6
The following variation of Example 4 obtains its input from the file DEMOGRAP.TXT. The second Call
statement uses different variable names for the arguments to show that using the same argument names is
not necessary. See Figure 3-2.
DEMOGRAP.TXT contains the following two lines: