Only accept digits for textbox

Question

I found this code for making my textbox only accept numbers.

Private Sub TextBox1_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
    Dim allowedChars As String = "0123456789"
    If allowedChars.IndexOf(e.KeyChar) = -1 Then
        ' Invalid Character
        e.Handled = True
    End If
End Sub

But... the user can't delete the numbers using the backspace button. How do I do then?

Answer 1

 Private Sub txtValue_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles                 txtValue.KeyPress
        'Dim allowedChars As String = "0123456789"
        'If allowedChars.IndexOf(e.KeyChar) = -1 Then
        '    ' Invalid Character
        '    e.Handled = True
        'End If
        'If (e.KeyChar = Microsoft.VisualBasic.Chr(8)) Then
        '    e.Handled = True
        'End If
        If Char.IsDigit(e.KeyChar) = False And Char.IsControl(e.KeyChar) = False Then
            e.Handled = True
        End If
    End Sub                                

Answer 2

Private Sub TMarksTextBox_KeyPress(sender As Object, e As KeyPressEventArgs) Handles TMarksTextBox.KeyPress
        If e.KeyChar < "0" OrElse e.KeyChar > "9" AndAlso e.KeyChar <> ControlChars.Back Then
            e.Handled = True
        End If
End Sub

Answer 3

When I have had the requirement of an input which only accepts numbers, I have typically used the NumericUpDown class. It handles limits and decimals too.

Answer 4

 Private Sub txtValue_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtValue.KeyPress
    Dim allowedChars As String = "."
    'If allowedChars.IndexOf(e.KeyChar) = -1 Then
    '    ' Invalid Character
    '    e.Handled = True
    'End If
    'If (e.KeyChar = Microsoft.VisualBasic.Chr(8)) Then
    '    e.Handled = True
    'End If
    If Char.IsDigit(e.KeyChar) = False And Char.IsControl(e.KeyChar) = False And allowedChars.IndexOf(e.KeyChar) = -1 Then
        e.Handled = True
    End If
End Sub

Answer 5

Use this code, it will help you

Public Function OnlyDigitsOnKeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs)

Try

    If System.Char.IsDigit(e.KeyChar) = False And e.KeyChar <> Microsoft.VisualBasic.Chr(8)        And e.KeyChar <> Microsoft.VisualBasic.Chr(46) Or (InStr(sender.text, ".") > 0 And  e.KeyChar = Microsoft.VisualBasic.Chr(46)) 
    Then
                e.Handled = True
    End If
        Catch ex As Exception
            Common.ErrorHandler(ex)
        End Try
End Function

Answer 6

You also need to handle pasted text (there may not be a keypress). The best way to do this is with a MaskedTextBox.