The Code Behind the Buttons

     At this point we have the option calculator interface and the code that can calculate an option price.

     To make our calculator actually do something, we need to add the code behind the buttons, so that when the user pushes a button, the calculation is made and the results are displayed on the interface.

     At the same time, we will also add some functions that create option legs, set startup parameters, and perform various checks.

     In your Visual Basic project, click on the tab that says "Form1.vb". You should see the code that we added previously for testing the names, that starts "Sub TestNames()" and ends "End Sub". Select that entire Sub and press your delete key to get rid of it. It serves no purpose in the completed calculator.

      If there is already a line that starts "Private Sub Form1_Load", get rid of that and the "End Sub" below it also. It will be replaced with the code you are pasting.

     Now, copy all the code below and paste it to a blank line between "Public Class Form1" and "End Class".

Friend leg1 as EquityOption Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Dim dt As Date = startupdate() Leg1ExpirationDate.Value = dt Messages.Text = "Reminder: Double-Click any number to change it quickly" Messages.ForeColor = Color.Blue End Sub Private Sub FindButtonsHandler(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles B_FindPrice.Click, B_FindIV.Click createlegs() If checkdates() = True Then If sender.name = "B_FindPrice" Then setprices() If Dividends.Value > 0 Then Messages.Text = "Option Prices on Dividend Paying stocks are approximate" Else Messages.Text = "Option Price calculated from IV" End If Else setvolatility() If Dividends.Value > 0 Then Messages.Text = "Option Prices on Dividend Paying stocks are approximate" Else Messages.Text = "IV calculated from Option Price" End If End If setvalues() Messages.ForeColor = Color.DarkGreen Else setzeros() Messages.ForeColor = Color.Red Messages.Text = "Expiration date is on or before the Entry date" End If End Sub Private Sub ChangeExp_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Leg1ExpPrev.Click, Leg1ExpNext.Click Dim direction As Integer = 1 If sender.name.contains("Prev") Then direction = -1 End If Leg1ExpirationDate.Value = changeexpiration(Leg1ExpirationDate.Value, direction) End Sub Private Sub createlegs() 'each option leg belongs to the EquityOption class leg1 = New EquityOption(Leg1Type.Text, Leg1Contracts.Value, Leg1EntryDate.Value, Leg1StockPrice.Value, Leg1StrikePrice.Value, Leg1ExpirationDate.Value, Leg1OptionPrice.Value, Leg1IV.Value, True, InterestRate.Value, Dividends.Value) End Sub Private Function checkdates() As Boolean Return leg1.expirationafterentry End Function Function startupdate() As Date Dim dt As Date = changeexpiration(Now.Date, 0) If DateDiff(DateInterval.Day, Now.Date, dt) > 0 Then Return dt Else Return changeexpiration(Now.Date, 1) End If End Function Private Sub setprices() Leg1OptionPrice.Value = leg1.price End Sub Private Sub setvolatility() Leg1IV.Value = leg1.volatility End Sub Private Sub setvalues() Leg1Value.Text = leg1.totalvalue(Leg1OptionPrice.Value) Leg1Value.BackColor = leg1.colorize End Sub Private Sub setzeros() Leg1Value.Text = FormatCurrency(0) Leg1Value.BackColor = Color.Gray End Sub

Save your project.