The RadioButton Control

' --- Reading which button is selected (If/ElseIf chain) ---
Private Sub btnConfirm_Click(...) Handles btnConfirm.Click
    Dim size As String
    If     rbSmall.Checked  Then size = "Small"
    ElseIf rbMedium.Checked Then size = "Medium"
    ElseIf rbLarge.Checked  Then size = "Large"
    Else                         size = "(none selected)"
    End If
    lblOrder.Text = $"Size: {size}"
End Sub

' --- Setting a default selection on Form_Load ---
Private Sub Form1_Load(...) Handles MyBase.Load
    rbMedium.Checked = True   ' sets Medium; Small and Large become False automatically
End Sub

' --- CheckedChanged fires TWICE per click ---
' Once when the OLD button loses selection (Checked → False)
' Once when the NEW button gains selection (Checked → True)
' Guard with If rb.Checked Then to run code only once:
Private Sub AnySize_CheckedChanged(...) Handles
        rbSmall.CheckedChanged, rbMedium.CheckedChanged, rbLarge.CheckedChanged

    Dim rb = DirectCast(sender, RadioButton)
    If Not rb.Checked Then Return   ' ignore the "unchecked" fire

    Select Case rb.Name
        Case "rbSmall"  : lblPrice.Text = "RM 8.00"
        Case "rbMedium" : lblPrice.Text = "RM 10.00"
        Case "rbLarge"  : lblPrice.Text = "RM 12.50"
    End Select
End Sub

' --- Using Tag to store numeric values instead of comparing strings ---
' In Designer, set rbSmall.Tag="8.00", rbMedium.Tag="10.00", rbLarge.Tag="12.50"
Private Sub AnySize_CheckedChanged2(...) Handles
        rbSmall.CheckedChanged, rbMedium.CheckedChanged, rbLarge.CheckedChanged
    Dim rb = DirectCast(sender, RadioButton)
    If Not rb.Checked Then Return
    Dim price = CDec(rb.Tag)
    lblPrice.Text = price.ToString("C2")
End Sub

' Two independent groups — each GroupBox is its own selection scope.
' Selecting rbCheese in grpCrust has NO effect on grpSauce buttons.

' Reading both groups to build an order
Private Sub btnOrder_Click(...) Handles btnOrder.Click
    Dim crust  = GetSelected(grpCrust)    ' returns Text of checked button
    Dim sauce  = GetSelected(grpSauce)
    Dim size   = GetSelected(grpSize)
    lblSummary.Text = $"{size} pizza, {crust} crust, {sauce} sauce"
End Sub

' Generic helper: find checked button in any container
Private Function GetSelected(container As Control) As String
    Dim rb = container.Controls.OfType(Of RadioButton)() _
                       .FirstOrDefault(Function(r) r.Checked)
    Return If(rb IsNot Nothing, rb.Text, "(none)")
End Function

' Generic helper using Tag value instead of Text
Private Function GetSelectedTag(Of T)(container As Control) As T
    Dim rb = container.Controls.OfType(Of RadioButton)() _
                       .FirstOrDefault(Function(r) r.Checked)
    If rb IsNot Nothing AndAlso rb.Tag IsNot Nothing Then
        Return CType(rb.Tag, T)
    End If
    Return Nothing
End Function

' Programmatically select a button by value
Private Sub SelectByTag(container As Control, tagValue As Object)
    For Each rb In container.Controls.OfType(Of RadioButton)()
        If rb.Tag?.ToString() = tagValue.ToString() Then
            rb.Checked = True
            Return
        End If
    Next
End Sub

' Build a group of RadioButtons at runtime from a list of options
Private Sub BuildRadioGroup(panel As Panel, options() As String,
                              defaultIndex As Integer = 0)
    panel.Controls.Clear()
    Dim y = 8
    For i = 0 To options.Length - 1
        Dim rb As New RadioButton With {
            .Text     = options(i),
            .Tag      = i,
            .Checked  = (i = defaultIndex),
            .Location = New Point(8, y),
            .AutoSize = True
        }
        AddHandler rb.CheckedChanged, AddressOf DynamicRb_CheckedChanged
        panel.Controls.Add(rb)
        y += 26
    Next
End Sub

Private Sub DynamicRb_CheckedChanged(sender As Object, e As EventArgs)
    Dim rb = DirectCast(sender, RadioButton)
    If Not rb.Checked Then Return   ' double-fire guard
    lblResult.Text = $"Selected: {rb.Text} (index {rb.Tag})"
End Sub

' Get selected index from any RadioButton group panel
Private Function GetSelectedIndex(panel As Panel) As Integer
    Dim rb = panel.Controls.OfType(Of RadioButton)() _
                   .FirstOrDefault(Function(r) r.Checked)
    Return If(rb IsNot Nothing, CInt(rb.Tag), -1)
End Function

' Load survey questions from a list
Dim satisfactionOptions = {"Very Satisfied", "Satisfied", "Neutral", "Dissatisfied"}
BuildRadioGroup(pnlSatisfaction, satisfactionOptions, defaultIndex:=1)

' Save a survey response
Private Sub btnSubmit_Click(...) Handles btnSubmit.Click
    Dim q1 = GetSelectedIndex(pnlQ1)
    Dim q2 = GetSelectedIndex(pnlQ2)
    Dim q3 = GetSelectedIndex(pnlQ3)
    If q1 = -1 OrElse q2 = -1 OrElse q3 = -1 Then
        MessageBox.Show("Please answer all questions.")
        Return
    End If
    SaveResponse(q1, q2, q3)
End Sub

' In the Designer:
'   1. Add a Panel (pnlTabs) with FlowLayout, horizontal
'   2. Add RadioButtons: rbDay, rbWeek, rbMonth, rbYear
'   3. Set ALL to Appearance = Appearance.Button, FlatStyle = Flat
'   4. Style with BackColor, ForeColor as needed
'   5. They share pnlTabs as container → mutually exclusive automatically

Private Sub Form1_Load(...) Handles MyBase.Load
    rbDay.Checked = True   ' default tab
End Sub

Private Sub AnyTab_CheckedChanged(...) Handles
        rbDay.CheckedChanged, rbWeek.CheckedChanged,
        rbMonth.CheckedChanged, rbYear.CheckedChanged

    Dim rb = DirectCast(sender, RadioButton)
    If Not rb.Checked Then Return

    ' Hide all content panels, show the relevant one
    pnlDay.Visible   = rbDay.Checked
    pnlWeek.Visible  = rbWeek.Checked
    pnlMonth.Visible = rbMonth.Checked
    pnlYear.Visible  = rbYear.Checked

    ' Or use Select Case on rb.Name:
    Select Case rb.Name
        Case "rbDay"   : LoadDayData()
        Case "rbWeek"  : LoadWeekData()
        Case "rbMonth" : LoadMonthData()
        Case "rbYear"  : LoadYearData()
    End Select
End Sub

' Subscription plan form:
' RadioButtons choose the plan tier (Basic / Pro / Enterprise)
' CheckBoxes choose optional add-ons (some disabled for Basic)

Private ReadOnly _plans As New Dictionary(Of String, Decimal) From {
    {"Basic", 29.0}, {"Pro", 79.0}, {"Enterprise", 199.0}
}
Private ReadOnly _addons As New Dictionary(Of String, Decimal) From {
    {"Extra Storage", 10.0}, {"Priority Support", 20.0}, {"Analytics", 15.0}
}

Private Sub AnyPlan_CheckedChanged(...) Handles
        rbBasic.CheckedChanged, rbPro.CheckedChanged, rbEnterprise.CheckedChanged
    Dim rb = DirectCast(sender, RadioButton)
    If Not rb.Checked Then Return

    ' Basic plan cannot have add-ons
    Dim isBasic = rbBasic.Checked
    chkStorage.Enabled  = Not isBasic
    chkSupport.Enabled  = Not isBasic
    chkAnalytics.Enabled = Not isBasic
    If isBasic Then
        chkStorage.Checked   = False
        chkSupport.Checked   = False
        chkAnalytics.Checked = False
    End If
    UpdateTotal()
End Sub

Private Sub UpdateTotal()
    Dim planName = GetSelected(grpPlan)
    Dim total    = _plans(planName)
    If chkStorage.Checked   Then total += _addons("Extra Storage")
    If chkSupport.Checked   Then total += _addons("Priority Support")
    If chkAnalytics.Checked Then total += _addons("Analytics")
    lblTotal.Text = $"Monthly total: {total:C2}"
End Sub