Label.Text to ("c") Help

Question

Can someone tell me why I can not assign the same ("c") to my lblPart as I did my other labels? and also advise how to get the sum of all labels. Thanks.

Public Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click
Dim Sum1 As Double
Dim Result As Double
'Dim lblLabor As Double '<<< rename lblLabor
Dim CalcMiscChages As Double
Dim SumMisc As Double
Dim dblBoxLabor As Double
Dim dblBoxParts As Double
Dim dbllblLabor As Double
Dim dbllblParts As Double
Dim dbllblTax As Double
Dim decTotalCharges As Double
Dim decTax As Double

    If ValidateInputFields() Then

        Result = CalcOilLubeCharges(dblOilChange, dblLubeJob) + CalcMiscCharges(dblInspection, dblReplaceMuffler, dblTireRotation) + CalcFlushes(dblRadiatorFlush, dblTransmissionFlush)

        lblLabor.Text = (txtBoxLabor.Text + Result).ToString("C")
        lblParts.Text = dectxtBoxLabor
        lblTax.Text = (txtBoxParts.Text * decTAX_RATE).ToString("c")

Answer

Probably dectxtBoxLabor is not a number.

To sum the labels, in VB you can try this: Val(lblLabor.Text) + Val(lblParts.Text) + Val(lblTax.Text), but there are more recommendations too. It seems easier to define and sum directly numeric variables.

Answer

You could use a custom label which has methods to set .Text as a specific format. Here we have one with several overloads with examples for two of them.

Custom label

Imports System.ComponentModel  
  
Public Class CurrencyFormattedLabel  
    Inherits Label  
  
    Public Sub New()  
        DoubleFormat = "c"  
    End Sub  
  
    Public Sub SetDoubleValue(value As Double)  
        Text = value.ToString(DoubleFormat)  
    End Sub  
    Public Sub SetDoubleValue(caption As String, value As Double)  
        Text = value.ToString(DoubleFormat)  
        Text = $"{caption} {value.ToString(DoubleFormat)}"  
    End Sub  
    Public Sub SetDoubleValue(value1 As Double, value2 As Double)  
        Text = (value1 + value2).ToString(DoubleFormat)  
    End Sub  
    Public Sub SetDoubleValue(caption As String, value1 As Double, value2 As Double)  
        Text = $"{caption} {(value1 + value2).ToString(DoubleFormat)}"  
    End Sub  
    Public Sub SetDoubleValue(caption As String, ParamArray args() As Double)  
        Text = $"{caption} {args.Sum().ToString(DoubleFormat)}"  
    End Sub  
    Public Sub SetDoubleValue(ParamArray args() As Double)  
        Text = args.Sum().ToString(DoubleFormat)  
    End Sub  
  
      
    Public Property DoubleFormat As String  
End Class

Usage

Public Class Form1  
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click  
        CurrencyFormattedLabel1.SetDoubleValue("Total", 123.99, 23, 34.22)  
    End Sub  
  
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click  
        CurrencyFormattedLabel1.SetDoubleValue(123.99, 23.76, 34.22)  
    End Sub  
End Class

Answer

In regards to calculate total charges, create a class such as below.

Perform assertions and calculations in PerformCalculation, use CalculateTax to calculate tax and if displaying in a label we use TotalLabel.Text = CalculateOrder.PresentTotal.

Public Class CalculateOrder
    Public Shared Property MiscellaneousCharges As Double
    Public Shared Property MiscellaneousSum As Double
    Public Shared Property Labor As Double
    Public Shared Property Parts As Double
    Public Shared Property Tax As Double
    Public Shared ReadOnly Property Total As Double
        Get
            Return PerformCalculation()
        End Get
    End Property
    Public Shared ReadOnly Property PresentTotal As String
        Get
            Return Total.ToString("C")
        End Get
    End Property
    Private Shared Function PerformCalculation() As Double
        Throw New NotImplementedException()
    End Function
    Private Shared Function CalculateTax() As Double
        Throw New NotImplementedException()
    End Function
End Class

Mockup usage

CalculateOrder.MiscellaneousCharges = 1
CalculateOrder.Labor = 1
CalculateOrder.Parts = 1
TotalLabel.Text = CalculateOrder.PresentTotal

Now we can augment the above by adding in an event if something goes wrong

Public Class CalculateOrder

    Public Delegate Sub OnException(sender As String)
    Public Shared Event OnExceptionEvent As OnException

    Public Shared Property MiscellaneousCharges As Double
    Public Shared Property MiscellaneousSum As Double
    Public Shared Property Labor As Double
    Public Shared Property Parts As Double
    Public Shared Property Tax As Double
    Public Shared ReadOnly Property Total As Double
        Get
            Return PerformCalculation()
        End Get
    End Property
    Public Shared ReadOnly Property PresentTotal As String
        Get
            Return Total.ToString("C")
        End Get
    End Property
    Private Shared Function PerformCalculation() As Double
        Throw New NotImplementedException()
    End Function
    Private Shared Function CalculateTax() As Double
        Throw New NotImplementedException()
    End Function
End Class

In the form

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    AddHandler CalculateOrder.OnExceptionEvent, AddressOf CalculationError
End Sub

Private Sub CalculationError(sender As String)
    Throw New NotImplementedException()
End Sub

Notes

Throw New NotImplementedException() represent work needs to be done e.g. assertions such as divide by zero, invalid values etc. and do the calculations
If you need to perform calculations on each part per-say you of course need to account for that.
How to use the event sample RaiseEvent OnExceptionEvent("Invalid amount")
When there are additional question not specific to the original question close out the first thread when satisfied then open a new thread/question.

Label.Text to ("c") Help

3 answers

Custom label

Usage