Restricting a text box to only include numbers between 0 and 100

Question

_{Saturday, June 29, 2013 1:36 AM}

Ok, I want to restrict a text box to only allow numbers between 0 and 100 (including decimals), i've tried many many ways, can anyone please shed some light on this problem? thankyou

All replies (7)

_{Saturday, June 29, 2013 1:52 AM ✅Answered}

You should post the code that you have used an explain why it didn't do what you wanted, or what the errors where.  Otherwise you are just going to get suggestions that you have already tried and dismissed.

You need to decide on how the user interaction is going to work.  Do you want to check the input character by character, or do you want to wait until focus leaves the textbox?  Do you want to sflash up a warning, ignore invalid chaacters, or simply adjust the entered value to the allowed range?

If you want to handle it on a character by character basis, us the textbox texxt changed event and examine the contents of the textbox after each change.
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.textchanged.aspx

If you want to handle it when the focus moves on, use the validating events.
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.validating.aspx

A better choice might be to use a control specifically designed for the type of input.  The options are disucssed here:
http://msdn.microsoft.com/en-us/library/ms229603.aspx

_{Saturday, June 29, 2013 2:18 AM ✅Answered}

I think you have a design problem. More thinking + a familiarity with "the way things are done" is the solution not 'solving' this fiasco.

Renee

"MODERN PROGRAMMING is deficient in elementary ways BECAUSE of problems INTRODUCED by MODERN PROGRAMMING." Me

_{Saturday, June 29, 2013 2:40 AM ✅Answered}

Try something like this

Option Strict On
Public Class Form1
    Friend WithEvents TextBox1 As New TextBox With {.Parent = Me}
    Private Sub TextBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyDown
        If Char.IsDigit(ChrW(e.KeyCode)) Then
        ElseIf e.KeyCode = Keys.Back Then
        ElseIf e.KeyCode = Keys.Delete Then
        ElseIf e.KeyCode = Keys.Up Then
        ElseIf e.KeyCode = Keys.Down Then
        ElseIf e.KeyCode = Keys.Left Then
        ElseIf e.KeyCode = Keys.Right Then
        ElseIf e.KeyCode = Keys.OemPeriod Then
        Else
            e.Handled = True
            e.SuppressKeyPress = True
        End If
    End Sub
    Private Sub TextBox1_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.LostFocus
        Dim Adjusted As String = adjInput(0, 100, TextBox1.Text)
        TextBox1.Text = Adjusted
        TextBox1.SelectionStart = TextBox1.Text.Length - 1
        TextBox1.SelectionLength = 0
    End Sub
    Sub ShowMessage1()
        MessageBox.Show("Your value was not within range!(0-100)", "Input value adjusted!", MessageBoxButtons.OK, MessageBoxIcon.Warning)
    End Sub
    Function adjInput(ByVal Min As Decimal, ByVal Max As Decimal, ByVal Input As String) As String
        Dim Value As Decimal
        If Not Decimal.TryParse(Input, Value) Then Return "0"
        If Value > Max Then Value = Max : ShowMessage1()
        If Value < Min Then Value = Min : ShowMessage1()
        Return Math.Round(Value, 3).ToString
    End Function
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        'When you click this button the textbox will lose focus & the inputted value will be adusted automatically
        MsgBox(TextBox1.Text)
    End Sub
End Class

“If you want something you've never had, you need to do something you've never done.”

*This post does not reflect the opinion of Microsoft, or its employees.

_{Saturday, June 29, 2013 3:22 AM ✅Answered}

Maybe this.

http://msdn.microsoft.com/en-us/library/System.Decimal.aspx

Public Class Form1

    Dim i As Decimal = 0

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.Text = "Testing for Decimal in TextBox"
    End Sub

    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
        Try
            i = Decimal.Parse(TextBox1.Text, Globalization.NumberStyles.AllowDecimalPoint)
        Catch ex As Exception
            Dim ToolTip1 As New ToolTip
            ToolTip1.IsBalloon = True
            ToolTip1.ToolTipIcon = ToolTipIcon.Error
            ToolTip1.ToolTipTitle = "ONLY USE DECIMALS FROM 0 TO 100"
            ToolTip1.Show("Style is not a Decimal value", TextBox1, New Point(0, -80), 2500)
            TextBox1.Text = ""
        End Try
        If i >= 0 AndAlso i <= 100 Then
            Exit Sub
        Else
            Dim ToolTip1 As New ToolTip
            ToolTip1.IsBalloon = True
            ToolTip1.ToolTipIcon = ToolTipIcon.Error
            ToolTip1.ToolTipTitle = "ONLY USE DECIMALS FROM 0 TO 100"
            ToolTip1.Show("Value was out of range", TextBox1, New Point(0, -80), 2500)
            TextBox1.Text = ""
        End If
    End Sub

End Class

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_{Saturday, June 29, 2013 3:28 AM ✅Answered}

JB,

My two cents worth follows: Don't restrict the users to anything -- let them type in whatever they want but use the .Validating Event to then check what they've typed.

If it doesn't pass the tests (what if it's just text that cannot be converted to a type double/decimal?) which would include the range of acceptable values, then advise them and set e.Cancel to true -- BUT -- give them an out lest they can't even close the program.

I won't go into all of that unless you ask but that's how I'd do it, so for what it's worth ... :)

Please call me Frank :)

_{Saturday, June 29, 2013 4:24 PM ✅Answered}

Instead of a Textbox, why not use a NumericUpDown control?  The user will only be able to select or enter values between the minimum and maximum.  The default setting is for a minimum value of 0 and maximum of 100, which can be changed.  It will also work with decimal values if you set the Decimal property to the number of decimal places. 

Solitaire

_{Saturday, June 29, 2013 3:42 AM}

Agreed here also.