Displaying Input into textbox

Question

I am trying to display a calculation into a TextBox, but having trouble with getting it to show. I want it to show once all input fields are true.

Public Class VehicleAudit

 Private Sub Calculate()
    Dim validMiles As Boolean = False
    Dim validPercent As Boolean = False
    Dim validAvg As Boolean = False

    Dim inputtedMiles As Double
    Dim inputtedPercent As Double
    Dim inputtedAvgCost As Double
    Dim servTruck As Integer
    Try
        inputtedMiles = Double.Parse(txtMilesDriven.Text)
        inputtedPercent = Double.Parse(txtPercent.Text)
        inputtedAvgCost = Double.Parse(txtAvgCost.Text)
    Catch ex As FormatException
        MessageBox.Show("Please enter all values and try again")
        Return
    End Try

    Dim cal As String = FormatCurrency(Convert.ToString(inputtedAvgCost * inputtedMiles * (1.0 + inputtedPercent))) + " dollars."

    ValidateBoxes(inputtedMiles, 0, 10000, "Miles must range from 0-10000.", validMiles)
    ValidateBoxes(inputtedPercent, 0.1, 0.5, "Please enter percent from .10 to .50", validPercent)
    ValidateBoxes(inputtedAvgCost, 0.25, 0.75, " Please enter Average cost from .25 to .75", validAvg)

    If (validAvg And validMiles And validPercent) Then
        Dim totalCost As Double
        If boxVehicleSelect.SelectedIndex = 9 Then
            servTruck = inputtedMiles / 100 'this way we lose precision using the integer, so values below 100s are dropped.
            totalCost = servTruck * 15.46
        Else
            totalCost = inputtedAvgCost * inputtedMiles * (1.0 + inputtedPercent)
        End If
    End If


End Sub

Private Sub txtTotalCost_TextChanged(ByVal Calculate As String, e As EventArgs) Handles txtTotalCost.TextChanged

End Sub

I can't see where you are changing the variable at (validMiles, validPercent and validAvg). You are passing them into ValidateBoxes, but what does that do? Please update question with this. — Trevor
– Trevor, Commented Jul 8, 2015 at 16:01
Private Sub ValidateBoxes(ByVal boxVal As Double, ByVal testLowVal As Double, ByVal testHighVal As Double, ByVal err As String, ByRef errCheck As Boolean) If (boxVal < testLowVal Or boxVal > testHighVal) Then MessageBox.Show(err) Else errCheck = True End If End Sub — Justyne Testerman
– Justyne Testerman, Commented Jul 8, 2015 at 16:11
I didn't put it because its a method for validating the input. I just want to take that calculate method and pass the result into the txtTotalCost textBox — Justyne Testerman
– Justyne Testerman, Commented Jul 8, 2015 at 16:12
Perhaps this is the issue: where are you setting the text on your output textbox? I'm thinking you need a line like txtTotalCost.Text = totalCost.ToString() somewhere after you calculate totalCost. — GalacticCowboy
– GalacticCowboy, Commented Jul 8, 2015 at 16:26
Ok I was trying to pass that method to the txtTotalCost text box object for display but your saying to just add the line to the calculate method for displaying correct. — Justyne Testerman
– Justyne Testerman, Commented Jul 8, 2015 at 16:30

Idle_Mind · Accepted Answer · 2015-07-08 18:25:43Z

1

You appear to already have a block that runs when all three values are "valid". Simply output that value at the bottom of it:

If (validAvg And validMiles And validPercent) Then
    Dim totalCost As Double
    If boxVehicleSelect.SelectedIndex = 9 Then
        servTruck = inputtedMiles / 100 'this way we lose precision using the integer, so values below 100s are dropped.
        totalCost = servTruck * 15.46
    Else
        totalCost = inputtedAvgCost * inputtedMiles * (1.0 + inputtedPercent)
    End If

    ' Output the computed "totalCost" some where.
    ' Here I'm using a Textbox called "txtTotalCost":
    txtTotalCost.Text = totalCost.ToString()

End If

Edit...

Also call your Calculate() method whenever one of your textboxes changes:

Private Sub TextChanged(sender As Object, e As EventArgs) Handles txtMilesDriven.TextChanged, txtAvgCost.TextChanged, txtPercent.TextChanged
    Calculate()
End Sub

Note how all three textboxes are listed after the handles keyword.

edited Jul 8, 2015 at 18:25

answered Jul 8, 2015 at 16:10

Idle_Mind

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6 Comments

Justyne Testerman Over a year ago

Yeah I tried that no output. Before I was using a button and when clicked it would display in a messagebox but not they want it to do it automatically without a button click.

Justyne Testerman Over a year ago

Yeah I had that originally in the txtTotalCost text box and no dice but when I add that to the other text boxes now its constantly running the loop. I can tell because every time I enter a numeric position it pops up my error message

Idle_Mind Over a year ago

Right...just get rid of that MessageBox line. You could blank out "txtTotalCost" instead. Then it will only update with a new value once all valid values have been entered.

Justyne Testerman Over a year ago

I removed that messagebox a long time ago, It is exactly as you see and have provided to me

Idle_Mind Over a year ago

Make sure you aren't calling Calculate() when txtTotalCost changes.

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