limit textbox input to numbers and range of numbers

Question

hello all again. i have one more issues, and hope is the last for now. How can I limit a textboxe's input to only numerical with certain range of values (eg -10 to 10) and with that happening while I type in the values?

Answer 1

Hi Johnkaragk,

check below similar thread

http://social.msdn.microsoft.com/forums/en-US/netfxbcl/thread/f5c0a64c-b9bf-4792-8a13-0b11a51339a6/

Best Regards,

Purvi

Answer 2

Thanx Purvi for ur answer. however the one you sent me is in C#. I am writing my program in VB in which im kind of a rookie!

Answer 3

Hi,

you use online C# to VB Converter to convert Purvi Code.

i converted sample code below

Private Sub textBox1_KeyPress(sender As Object, e As KeyPressEventArgs)
	If Not Char.IsNumber(e.KeyChar) Then
		e.Handled = True
	End If
End Sub


Private Sub textBox1_TextChanged(sender As Object, e As EventArgs)
	If Convert.ToDecimal(textBox1.Text) < 0 OrElse Convert.ToDecimal(textBox1.Text) > 60 Then
		MessageBox.Show("Valid Decimal Data: 0~60")
	End If
End Sub

Hope this help to you

Kalpesh

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Kalpesh Chhatrala | Software Developer | Rajkot | India

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Answer 4

Thank you Kalpesh that was helpful. I only have two problems. I cannot enter values less than 0 and the backspace is not working at all. Is there a way to fix that?

Answer 5

Hi johnkaragk,

This is not a Visual Studio Editor issue, I will move it to "Visual Basic General" forum for a better support.

Thank you for your understanding!

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Lucy Liu [MSFT]
MSDN Community Support | Feedback to us

Answer 6

Hi johnkaragk,

Welcome to the MSDN forum.

Instead of using Textchanged event and KeyPress event, I will suggest you to use leave event of textbox. It will check the number when the focus leaves the textbox. Here is a sample:

 Private Sub TextBox1_Leave(sender As System.Object, e As System.EventArgs) Handles TextBox1.Leave
        If Convert.ToDecimal(TextBox1.Text) < -10 OrElse Convert.ToDecimal(TextBox1.Text) > 10 Then
            MessageBox.Show("Valid Decimal Data: -10~10")
        End If
    End Sub

Hope this helps.

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Mark Liu-lxf [MSFT]
MSDN Community Support | Feedback to us

Answer 7

Hello,

Have you considered a NumericUpDown control? You can set min and max values and has up/down arrows to allow the user to not only add values from typing a value in but via the up/down arrows. If you don't like the up/down arrows they can be removed as shown in the custom control below.

Imports System.Drawing
Imports System.Windows.Forms
''' <summary>
''' Basically this control loses the spinners for incrementing
''' the control's value property and adds logic to handle key
''' down and key up to change this control's value honoring the
''' Minimum and Maximum value of this control.
''' </summary>
''' <remarks></remarks>
<ToolboxBitmap(GetType(NumericUpDown))> _
Public Class NumericEditBox
    Inherits System.Windows.Forms.NumericUpDown
    Public Sub New()
        MyBase.New()
        ' hide up/down control
        Controls(0).Visible = False
    End Sub
    Protected Overrides Sub OnTextBoxResize( _
        ByVal source As Object, ByVal e As System.EventArgs)
        ' without this code the up/down control still shows
        Controls(0).Size = New Size(0, ClientSize.Height)
        Controls(1).Size = New Size(ClientSize.Width, ClientSize.Height)
    End Sub
    Private Sub NumericEditBox_KeyDown( _
        ByVal sender As Object, _
        ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown
        Dim CurrentValue As Decimal = Value
        If e.KeyCode = Keys.Subtract Then
            Dim AllowMinus As Boolean = Minimum < 0
            If (CurrentValue - Increment) >= Minimum Then
                If Not AllowMinus Then
                    Dim TB As TextBox = DirectCast(Controls(1), TextBox)
                    TB.Text = TB.Text.Replace("-", "")
                    TB.Update()
                End If
                Value = CurrentValue - Increment
            End If
            e.SuppressKeyPress = True
        ElseIf e.KeyCode = Keys.Add Then
            If (CurrentValue + Increment) <= Maximum Then
                Value = CurrentValue + Increment
            End If
            e.SuppressKeyPress = True
        End If
    End Sub
End Class

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KSG

Answer 8

You can try this simple code:

Private Sub textBox1_KeyPress(sender As Object, e As KeyPressEventArgs)
	If e.KeyChar <> ControlChars.Back AndAlso e.KeyChar <> "-"C Then
		'allow backspace for deleting and minus simbol
		e.Handled = Not Char.IsNumber(e.KeyChar)
		'allow numbers only
		If Not e.Handled Then
			Dim num As Integer = Integer.Parse(String.Format("{0}{1}", If(textBox1.Text = String.Empty, "", textBox1.Text), e.KeyChar.ToString()))
			If num < -10 OrElse num > 10 Then
				e.Handled = True
			End If
		End If
	End If
End Sub

It works, tested.

bye

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Mitja

Answer 9

I think the best approach is to create a custom control by inheriting from a TextBox or NumericUpDown.  Don't clutter up your Form class with code that does not directly apply with managing the behavior of form instance.  This is known as "Separation of Concerns" in Object Oriented Programming.   The numeric-only behavior is a behavior that is exclusive to the control.  The Form instance should manage user interaction with the controls and manage the interaction between controls.  The Form class should not contain code that alters the behaviors of controls.  Use separate classes to define behaviors. 

The code posted by Mitja could be included with a slight modification into a custom class that inherits TextBox.

Hope this helps. 

Rudy   =8^D

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