'    Project:   Variables and Constants
' Programmer:   Andy McCone
'       Date:   Jan 18th 2008
'Description:   This program takes the price and quantity of a
'               sales to give us the subtotal, tax and total
'               using local and module variables, as well as constants

Public Class mainForm
    'Module level Variables and Constants
    Dim m_numOfSalesCounterInteger As Integer
    Dim m_totalSalesDecimal As Decimal
    Const m_TAX_RATE_decimal As Decimal = 0.085D

    Private Sub calculateButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles calculateButton.Click

        Try
            'Declare Variables
            Dim quantityInteger As Integer
            Dim priceDecimal As Decimal
            Dim subTotalDecimal As Decimal
            Dim taxDecimal, totalDecimal As Decimal

            'Capture values in textboxes
            quantityInteger = Integer.Parse(quantityTextBox.Text)
            priceDecimal = Decimal.Parse(priceTextBox.Text)

            'Calculate the subtotal and tax
            subTotalDecimal = quantityInteger * priceDecimal
            taxDecimal = subTotalDecimal * m_TAX_RATE_decimal

            'Calculate Total
            totalDecimal = subTotalDecimal + taxDecimal

            'Display results
            taxLabel.Text = taxDecimal.ToString("c")
            totalPriceLabel.Text = FormatCurrency(totalDecimal)

            'Count the number of sales and display
            m_numOfSalesCounterInteger = m_numOfSalesCounterInteger + 1
            'm_numOfSalesCounterInteger += 1
            numOfSalesLabel.Text = FormatNumber(m_numOfSalesCounterInteger, 0)

            'Update running total of sales and display
            m_totalSalesDecimal = m_totalSalesDecimal + totalDecimal
            totalSalesLabel.Text = FormatCurrency(m_totalSalesDecimal)

        Catch ex As Exception

            'Error message for user
            MessageBox.Show("Please use only Numbers", "Errorr")

        End Try

    End Sub

    Private Sub exitButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles exitButton.Click

        'Close program
        Me.Close()

    End Sub
End Class