Answer to Question #254626 in Visual Basic for San

Question

I have to create an application that allows the user to pick an item from a list box and has to calculate its pricing in including vat, also 10% discount to loyal customers. How do I get the information on the list box once I selected that item and do all calculations. I want to program all this inside a button and I also need to input a number so I must know how much change I'm getting etc.

Answer 1

Public Class frmMain
    Private amount As Double
    Private total As Double
    Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click, btnCalculateChange.Click
        Dim prices() As Double = {5, 10, 7, 15}


        If lstItems.SelectedIndex <> -1 Then
            Dim number As Integer
            Integer.TryParse(txtNumber.Text, number)
            Double.TryParse(txtAmount.Text, amount)
            Dim subTotal As Double = number * prices(lstItems.SelectedIndex)
            Dim VAT As Double = subTotal * 0.06
            Dim discount As Double = subTotal * 0.1
            total = subTotal + VAT - discount
            txtVAT.Text = VAT.ToString("N2")
            txtDiscount.Text = discount.ToString("N2")
            txtTotal.Text = total.ToString("N2")
            btnCalculateChange.Enabled = True
           
        End If
    End Sub


    Private Sub btnCalculateChange_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculateChange.Click
        Dim change As Double = amount - total
        txtChange.Text = change.ToString("N2")
    End Sub
End Class

<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Class frmMain
    Inherits System.Windows.Forms.Form

    'Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overrides Sub Dispose(ByVal disposing As Boolean)
        Try
            If disposing AndAlso components IsNot Nothing Then
                components.Dispose()
            End If
        Finally
            MyBase.Dispose(disposing)
        End Try
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.lstItems = New System.Windows.Forms.ListBox()
        Me.btnCalculate = New System.Windows.Forms.Button()
        Me.Label1 = New System.Windows.Forms.Label()
        Me.txtNumber = New System.Windows.Forms.TextBox()
        Me.Label2 = New System.Windows.Forms.Label()
        Me.txtVAT = New System.Windows.Forms.TextBox()
        Me.Label3 = New System.Windows.Forms.Label()
        Me.txtDiscount = New System.Windows.Forms.TextBox()
        Me.Label4 = New System.Windows.Forms.Label()
        Me.txtAmount = New System.Windows.Forms.TextBox()
        Me.Label5 = New System.Windows.Forms.Label()
        Me.txtTotal = New System.Windows.Forms.TextBox()
        Me.Label6 = New System.Windows.Forms.Label()
        Me.txtChange = New System.Windows.Forms.TextBox()
        Me.btnCalculateChange = New System.Windows.Forms.Button()
        Me.SuspendLayout()
        '
        'lstItems
        '
        Me.lstItems.FormattingEnabled = True
        Me.lstItems.Items.AddRange(New Object() {"Item 1  - price 5 ", "Item 2  - price 10", "Item 3  - price 7", "Item 4  - price 15"})
        Me.lstItems.Location = New System.Drawing.Point(12, 12)
        Me.lstItems.Name = "lstItems"
        Me.lstItems.Size = New System.Drawing.Size(101, 186)
        Me.lstItems.TabIndex = 0
        '
        'btnCalculate
        '
        Me.btnCalculate.Location = New System.Drawing.Point(131, 175)
        Me.btnCalculate.Name = "btnCalculate"
        Me.btnCalculate.Size = New System.Drawing.Size(75, 23)
        Me.btnCalculate.TabIndex = 1
        Me.btnCalculate.Text = "Calculate"
        Me.btnCalculate.UseVisualStyleBackColor = True
        '
        'Label1
        '
        Me.Label1.AutoSize = True
        Me.Label1.Location = New System.Drawing.Point(136, 22)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(73, 13)
        Me.Label1.TabIndex = 2
        Me.Label1.Text = "Enter number:"
        '
        'txtNumber
        '
        Me.txtNumber.Location = New System.Drawing.Point(215, 19)
        Me.txtNumber.Name = "txtNumber"
        Me.txtNumber.Size = New System.Drawing.Size(100, 20)
        Me.txtNumber.TabIndex = 3
        '
        'Label2
        '
        Me.Label2.AutoSize = True
        Me.Label2.Location = New System.Drawing.Point(155, 48)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(54, 13)
        Me.Label2.TabIndex = 2
        Me.Label2.Text = "VAT (6%):"
        '
        'txtVAT
        '
        Me.txtVAT.Location = New System.Drawing.Point(215, 45)
        Me.txtVAT.Name = "txtVAT"
        Me.txtVAT.ReadOnly = True
        Me.txtVAT.Size = New System.Drawing.Size(100, 20)
        Me.txtVAT.TabIndex = 3
        '
        'Label3
        '
        Me.Label3.AutoSize = True
        Me.Label3.Location = New System.Drawing.Point(128, 74)
        Me.Label3.Name = "Label3"
        Me.Label3.Size = New System.Drawing.Size(81, 13)
        Me.Label3.TabIndex = 2
        Me.Label3.Text = "Discount (10%):"
        '
        'txtDiscount
        '
        Me.txtDiscount.Location = New System.Drawing.Point(215, 71)
        Me.txtDiscount.Name = "txtDiscount"
        Me.txtDiscount.ReadOnly = True
        Me.txtDiscount.Size = New System.Drawing.Size(100, 20)
        Me.txtDiscount.TabIndex = 3
        '
        'Label4
        '
        Me.Label4.AutoSize = True
        Me.Label4.Location = New System.Drawing.Point(136, 126)
        Me.Label4.Name = "Label4"
        Me.Label4.Size = New System.Drawing.Size(73, 13)
        Me.Label4.TabIndex = 2
        Me.Label4.Text = "Enter amount:"
        '
        'txtAmount
        '
        Me.txtAmount.Location = New System.Drawing.Point(215, 123)
        Me.txtAmount.Name = "txtAmount"
        Me.txtAmount.Size = New System.Drawing.Size(100, 20)
        Me.txtAmount.TabIndex = 3
        '
        'Label5
        '
        Me.Label5.AutoSize = True
        Me.Label5.Location = New System.Drawing.Point(175, 100)
        Me.Label5.Name = "Label5"
        Me.Label5.Size = New System.Drawing.Size(34, 13)
        Me.Label5.TabIndex = 2
        Me.Label5.Text = "Total:"
        '
        'txtTotal
        '
        Me.txtTotal.Location = New System.Drawing.Point(215, 97)
        Me.txtTotal.Name = "txtTotal"
        Me.txtTotal.ReadOnly = True
        Me.txtTotal.Size = New System.Drawing.Size(100, 20)
        Me.txtTotal.TabIndex = 3
        '
        'Label6
        '
        Me.Label6.AutoSize = True
        Me.Label6.Location = New System.Drawing.Point(162, 152)
        Me.Label6.Name = "Label6"
        Me.Label6.Size = New System.Drawing.Size(47, 13)
        Me.Label6.TabIndex = 2
        Me.Label6.Text = "Change:"
        '
        'txtChange
        '
        Me.txtChange.Location = New System.Drawing.Point(215, 149)
        Me.txtChange.Name = "txtChange"
        Me.txtChange.ReadOnly = True
        Me.txtChange.Size = New System.Drawing.Size(100, 20)
        Me.txtChange.TabIndex = 3
        '
        'btnCalculateChange
        '
        Me.btnCalculateChange.Enabled = False
        Me.btnCalculateChange.Location = New System.Drawing.Point(215, 175)
        Me.btnCalculateChange.Name = "btnCalculateChange"
        Me.btnCalculateChange.Size = New System.Drawing.Size(100, 23)
        Me.btnCalculateChange.TabIndex = 1
        Me.btnCalculateChange.Text = "Calculate change"
        Me.btnCalculateChange.UseVisualStyleBackColor = True
        '
        'frmMain
        '
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(342, 225)
        Me.Controls.Add(Me.txtChange)
        Me.Controls.Add(Me.Label6)
        Me.Controls.Add(Me.txtTotal)
        Me.Controls.Add(Me.Label5)
        Me.Controls.Add(Me.txtDiscount)
        Me.Controls.Add(Me.Label3)
        Me.Controls.Add(Me.txtVAT)
        Me.Controls.Add(Me.Label2)
        Me.Controls.Add(Me.txtAmount)
        Me.Controls.Add(Me.Label4)
        Me.Controls.Add(Me.txtNumber)
        Me.Controls.Add(Me.Label1)
        Me.Controls.Add(Me.btnCalculateChange)
        Me.Controls.Add(Me.btnCalculate)
        Me.Controls.Add(Me.lstItems)
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle
        Me.MaximizeBox = False
        Me.MinimizeBox = False
        Me.Name = "frmMain"
        Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
        Me.Text = "Discount Loyal Customers"
        Me.ResumeLayout(False)
        Me.PerformLayout()

    End Sub
    Friend WithEvents lstItems As System.Windows.Forms.ListBox
    Friend WithEvents btnCalculate As System.Windows.Forms.Button
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents txtNumber As System.Windows.Forms.TextBox
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents txtVAT As System.Windows.Forms.TextBox
    Friend WithEvents Label3 As System.Windows.Forms.Label
    Friend WithEvents txtDiscount As System.Windows.Forms.TextBox
    Friend WithEvents Label4 As System.Windows.Forms.Label
    Friend WithEvents txtAmount As System.Windows.Forms.TextBox
    Friend WithEvents Label5 As System.Windows.Forms.Label
    Friend WithEvents txtTotal As System.Windows.Forms.TextBox
    Friend WithEvents Label6 As System.Windows.Forms.Label
    Friend WithEvents txtChange As System.Windows.Forms.TextBox
    Friend WithEvents btnCalculateChange As System.Windows.Forms.Button

End Class