How to filter textbox input to numeric only?

Question

How do I suppress all data except numeric?

This is not working on KeyDown():

If e.KeyData < Keys.D0 Or e.KeyData > Keys.D9 Then
          


        

Answer 1

I suggest that you use regular expressions. You can search Google, like 'regular expression textbox only numeric' and I guess you'll come up with many examples.

For example, if you are in ASP.NET you can do it like:

<asp:TextBox 
    ID="txtPhoneNumber" 
    runat="server" 
    Text='<%#Bind("phoneNumber") %>' 
    MaxLength="15">
</asp:TextBox>

<asp:RegularExpressionValidator 
    ID="rfvUSerPhoneNumberValidate" 
    runat="server"
    ControlToValidate="txtPhoneNumber" 
    Display="Dynamic" 
    ValidationExpression="^[0-9]{1,15}$"
    ErrorMessage="Please enter only numeric value for Phone Number" 
    EnableViewState="true">
</asp:RegularExpressionValidator>

Answer 2

There are many ways to do this. I've had a quick stab at it and go this which works. I have used the KeyPress sub for the textbox, and pass each keypress to the IsNumber function.

NOTE: I have allowed the backspace key to be used in case you make a mistake with the numbers and want to deleted.

Take out the If e.KeyChar <> ChrW(Keys.Back) Then / End If part if you dont need the backspace.

    Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
    If e.KeyChar <> ChrW(Keys.Back) Then
        If Char.IsNumber(e.KeyChar) Then
        Else
            e.Handled = True
        End If
    End If
End Sub

Answer 3

 Public Class NumericTextBox : Inherits System.Windows.Forms.TextBox

 Protected Overrides Sub OnKeyPress(e As Windows.Forms.KeyPressEventArgs)
      If Char.IsDigit(e.KeyChar) Or
          Char.IsControl(e.KeyChar) Or
          e.KeyChar = lobalization.CultureInfo.CurrentCulture.NumberFormat.CurrencyDecimalSeparator Then
      MyBase.OnKeyPress(e)
    Else
        e.Handled = True
    End If
 End Sub

 End Class

Answer 4

This code will help you to restrict multiple TEXTBOX to accept only NUMERIC VALUE and BACKSPACE key. However you can remove If e.KeyChar <> ChrW(Keys.Back) Then and End If value from code when you don't want to accept backspace key. Enhanced version of the kevchadders solution in this thread.

Private Sub TextBox_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress, TextBox2.KeyPress, TextBox3.KeyPress
    If e.KeyChar <> ChrW(Keys.Back) Then
        If Char.IsNumber(e.KeyChar) Then
        Else
            e.Handled = True
        End If
    End If
End Sub

Answer 5

This is another way to restrict number inputs into textbox . using KEYPRESS Events

If Asc(e.KeyChar) <> 13 AndAlso Asc(e.KeyChar) <> 8 AndAlso Not IsNumeric(e.KeyChar) Then MessageBox.Show("Only Numbers") e.Handled = True End If End Sub hope it helps ! thnks ..

Answer 6

You can check Char.IsDigit(e.KeyChar), but the best thing to do in this case is to create a subclass of TextBox and override IsInputChar(). That way you have a reusable TextBox control that you can drop anywhere so you don't have to re-implement the logic.

(My VB is a bit rusty...)

Public Class NumericTextBox : Inherits TextBox

    Protected Overrides Function IsInputChar(Byval charCode As Char) As Boolean
        If (Char.IsControl(charCode) Or Char.IsDigit(charCode)) Then
            Return MyBase.IsInputChar(charCode)
        Else
            Return False
        End If
    End Function

End Class