Math operations with wpf textBox.

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Hi guys

I have a WPF Window with three textBoxes

txtPrice

txtTax

txtTotal

I want to write data in txtPrice and automatically fill the others textBoxes.

I write this code :

VB

Private Sub txtPrice_TextChanged(ByVal sender As Object, ByVal e As TextChangedEventArgs)
        Dim num1 As Decimal
        num1 = CDec(Val(txtPrice.Text) * 4 / 100)
        txtTax.Text = Math.Round(num1, 2)
    End Sub

    Private Sub txtTax_TextChanged(ByVal sender As Object, ByVal e As TextChangedEventArgs)
        Dim num2 As Decimal
        num2 = CDec(Val(txtPrice.Text) + CDec(Val(txtTax.Text))
        txtTotal.Text = Math.Round(num1, 2)
    End Sub

with my code txtTax vaalue is right and is decimal but txtTotal value is not a decimal.

e.g

txtPrice.Text = 534,46 txtTax.Text = 21,37 txtTotal.Text = 555

Thanks in advance

Posted 24-Jan-16 2:58am

jomachi

Updated 24-Jan-16 3:05am

v3

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Comments

[no name] 24-Jan-16 9:20am

I don't know VB and I did not look in Details to your Problem. But on a first glance " * 4 / 100" is maybe the problem. Try "* 4.0 / 100.0" or what I usually do: "* 4.0 * 0.01".

Sergey Alexandrovich Kryukov 24-Jan-16 13:54pm

Why do you use Round at all?
—SA

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Michael_Davies · Accepted Answer · 2016-01-24T03:29:00

Probably because the result in your example is a whole number. Math.Round will not return .00 even though you state decimal places, you need to use formatting:

VB

txtTotal.Text = Math.Round(num1,2).Tostring("0.00",CultureInfo.InvariantCulture)

You should also verify the content of the txtPrice.Text or you'll get exceptions if someone types non-numeric text.