Exercise This 6-1, asks us to create an application that uses a sub procedure to calculate the
Retail Price of an Item (Whole Sale Price + Mark up). It is a rather simple little exercise; but
useful because it introduces us to functions and sub procedures. Although it is not necessary to
do so, I have included second sub procedure to clear the form after calculation.
Start Program Code
Imports Microsoft.VisualBasic.ControlChars
Public Class Form1
'Class library
Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btnExit.Click
Me.Close() 'Stop Program and Close form
End Sub
Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btnClear.Click
Clear() 'call the clear sub procedure
End Sub
Private Sub btnGetRetail_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btnGetRetail.Click
Dim RetailPrice As Decimal
Dim numWS As Decimal
Dim numMarkUp As Decimal
Try
numWS = txtWholeSale.Text
numMarkUp = txtMarkUp.Text
Catch ex As Exception 'Catch error if not numbers
MessageBox.Show("WholeSale Cost and Mark UP %" & CrLf & "Must numbers both
be > 0", "INPUT ERROR!")
GoTo ReDo 'Jumo to end of event to allow correction
End Try
If numWS < 0 Or numMarkUp < 0 Then 'check if less than zero
MessageBox.Show("WholeSale Cost and Mark UP %" & CrLf & "Can not
be Negative Numbers", " Negative # ERROR")
GoTo ReDo
End If
numMarkUp = txtMarkUp.Text * 0.01 'Convert numMarkUP a percent
RetailPrice = CalculateRetail(numWS, numMarkUp) 'call the function
lblRetailPrice.Text = FormatCurrency(RetailPrice) 'display price
ReDo:
End Sub
Function CalculateRetail(ByVal decNum1, ByVal decNum2) As Decimal
'This function could be written as a sub procedure; but
'since I am sending the calculated value back to the
btnGetRetail_Click event
'a function works better
Dim RetailPrice As Decimal
RetailPrice = decNum1 + decNum1 * decNum2
Return RetailPrice
End Function
'returns this value to the calling sub procedure
Sub Clear()
'I included this sub as an example of a sub procedure.
'It is called by the btnClear_click event
txtWholeSale.Clear()
txtMarkUp.Clear()
lblRetailPrice.Text = ""
txtWholeSale.Focus()
End Sub
End Class