How to add/minus multiple checkbox values

Question

I'm using VB.net and I'm having trouble trying to add different values when I select checkboxes and diplaying the total in a textbox. When unchecking them, it should be subtracting the values. Here is my code

"totals" is my textbox

Dim total As Double

Private Sub cchstk_CheckStateChanged(sender As Object, e As EventArgs) Handles cchstk.CheckStateChanged
    If (cchstk.Checked = True) Then
        total = total + 109.99
        totals.Text = Double.Parse(total)
    ElseIf (chstk.Checked = False) Then
        total = total - 109.99
        totals.Text = Double.Parse(total)
    End If
End Sub

Private Sub cms_CheckStateChanged(sender As Object, e As EventArgs) Handles cms.CheckStateChanged
    If (cms.Checked = True) Then
        total = total + 79.99
        totals.Text = Double.Parse(total)
    ElseIf (chstk.Checked = False) Then
        total = total - 79.99
        totals.Text = Double.Parse(total)
    End If
End Sub

Private Sub prrdg_CheckStateChanged(sender As Object, e As EventArgs) Handles prrdg.CheckStateChanged
    If (prrdg.Checked = True) Then
        total = total + 49.99
        totals.Text = Double.Parse(total)
    ElseIf (chstk.Checked = False) Then
        total = total - 49.99
        totals.Text = Double.Parse(total)
    End If

End Sub

Private Sub gb_CheckStateChanged(sender As Object, e As EventArgs) Handles gb.CheckStateChanged
    If (gb.Checked = True) Then
        total = total + 29.99
        totals.Text = Double.Parse(total)
    ElseIf (chstk.Checked = False) Then
        total = total - 29.99
        totals.Text = Double.Parse(total)
    End If
End Sub

Private Sub nd_CheckStateChanged(sender As Object, e As EventArgs) Handles nd.CheckStateChanged
    If (nd.Checked = True) Then
        total = total + 29.99
        totals.Text = Double.Parse(total)
    ElseIf (chstk.Checked = False) Then
        total = total - 29.99
        totals.Text = Double.Parse(total)
    End If
End Sub`

In all of your event, you check for "chstk.Checked = False". Is this what you want? is chstk the right variable to use? — the_lotus
– the_lotus, Commented Aug 26, 2014 at 14:34
@the_lotus, good catch, i didn't saw this :-) another reason to use a single method instead of copy/pasting and adapting — Fredou
– Fredou, Commented Aug 26, 2014 at 14:35

Fredou · Accepted Answer · 2014-08-26 14:42:19Z

1

you only have to change all your Double.Parse(total) to total.ToString

you want to convert a number to string, not a number to a number.

also do not use double if you can, you will be hit by floating conversion issue

use decimal and you can also create a method to reduce the repetition of code

Dim total As Decimal

Private Sub ChangeValue(add As Boolean, value As Decimal)
    total += If(add, value, -value)
    TextBox1.Text = total.ToString
End Sub

Private Sub CheckBox1_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox1.CheckedChanged
    ChangeValue(DirectCast(sender, CheckBox).Checked, 109.99D)
End Sub

Private Sub CheckBox2_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox2.CheckedChanged
    ChangeValue(DirectCast(sender, CheckBox).Checked, 79.99D)
End Sub

Private Sub CheckBox3_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox3.CheckedChanged
    ChangeValue(DirectCast(sender, CheckBox).Checked, 49.99D)
End Sub

Private Sub CheckBox4_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox4.CheckedChanged
    ChangeValue(DirectCast(sender, CheckBox).Checked, 29.99D)
End Sub

Private Sub CheckBox5_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox5.CheckedChanged
    ChangeValue(DirectCast(sender, CheckBox).Checked, 29.99D)
End Sub

edited Aug 26, 2014 at 14:42

answered Aug 26, 2014 at 14:04

Fredou

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6 Comments

DOODpls Over a year ago

it adds now, but the unchecking part is broken. when i unchecked all, the value of total becomes negative. and sometimes when i unchecked it, it doesn't subtract.

Fredou Over a year ago

@DOODpls, what are the original state, all unchecked? some of them checked? all checked?

Fredou Over a year ago

@DOODpls, found the issue, do not use double if you can. use decimal instead

DOODpls Over a year ago

it is unchecked, then i checked it, and it adds, no problem, but when i unchecked it, some of the checkbox doesnt subtract its values, and some subtracts it and making the "total" to negative or sometime it doesnt subtact all the checkbox that i unchecked

Fredou Over a year ago

@DOODpls, in my testing i just created a new winform application, dropped 5 checkbox and a textbox on the form. if you have something different, update your question with more details

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