TextBox not editing after SelectAll in vb.net

I have an issue, The thing is I have to allow user to enter numeric value in text box up to one decimal point,

When all text selected and I try try to edit text by entering any numeric key, It wont let it change.

Here is the text box with value.

The code behind, Keypress

Private Sub TextBox1_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
    If Regex.IsMatch(TextBox1.Text, "\.\d") Then
        e.Handled = True
    End If
End Sub

Kindly anybody help or suggest better way.

I have added this code but I am unable to restrict user not to enter more then one decimal point value.

 If Not ((Asc(e.KeyChar) >= 48 And Asc(e.KeyChar) <= 57) Or Asc(e.KeyChar) = 46 Or Asc(e.KeyChar) = 8 Or Asc(e.KeyChar) = 127) Then
        e.KeyChar = ""
        e.Handled = False
    End If

回答1:

Try this: (not regex tho), but works great for numerics.

It allows for 1 x negative symbol, one fullstop (point), using backspace, and any numerics..

       Private Sub priceTextBox_KeyPress(sender As Object, e As KeyPressEventArgs) Handles priceTextBox.KeyPress
       If IsNumeric(e.KeyChar.ToString) = False Then

            If e.KeyChar.ToString = "." And priceTextBox.Text.Contains(".") Then e.Handled = True
            If e.KeyChar.ToString = "-" And priceTextBox.Text.Contains("-") Then e.Handled = True

            If e.KeyChar.ToString <> "." Then
                If e.KeyChar <> ControlChars.Back Then
                    If e.KeyChar <> "-" Then
                        e.Handled = True
                    End If
                End If
            End If
        End If
        End Sub

EDIT

This allows for the above numerics, as well as only 1 decimal point. I kept it simple with more code lines to show steps, so you can see what actually happens. I am sure it can be improved, this is a quick and dirty version...

Allows for Globalization of the decimal character

Also catches a "paste" into the textbox, that normally circumvents the keypress catch routines

Dim lastProperText As String = ""

Private Sub priceTextBox_TextChanged(sender As Object, e As EventArgs) Handles priceTextBox.TextChanged

  If priceTextBox.Text = "" Then Exit Sub
  If IsNumeric(priceTextBox.Text) = False Then priceTextBox.Text = lastProperText
  If _containsDecimal(priceTextBox.Text, 2) = True Then priceTextBox.Text = lastProperText

End Sub

Private Sub priceTextBox_KeyPress(sender As Object, e As KeyPressEventArgs) Handles priceTextBox.KeyPress
    Dim decimalSeparator As String = Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator

    If IsNumeric(e.KeyChar.ToString) = False Then

        If e.KeyChar.ToString = decimalSeparator And priceTextBox.Text.Contains(decimalSeparator) Then e.Handled = True
        If e.KeyChar.ToString = "-" And priceTextBox.Text.Contains("-") Then e.Handled = True

        'allow backspace here
        If e.KeyChar = ControlChars.Back Then Exit Sub

        If e.KeyChar.ToString <> decimalSeparator Then
            If e.KeyChar <> ControlChars.Back Then
                If e.KeyChar <> "-" Then

                    e.Handled = True

                End If
            End If
        End If
    End If

    'BUG FIX
    If priceTextBox.SelectionStart > priceTextBox.Text.Length - 2 Then
      If _containsDecimal(priceTextBox.Text, 1) = True Then e.Handled = True
    End If
    '/BUG FIX

    'keep last good format.. we will use this in case something gets apsted in that does not meet our format...
    lastProperText = priceTextBox.Text

End Sub

Private Function _containsDecimal(stringtoCheck As String, decimalNumber As Integer) As Boolean

    Dim decimalSeparator As String = Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator

    'check to allow only 1 decimal point
    Dim positionOfPoint As Integer = 0

    'get position of decimal point (.)
    positionOfPoint = InStr(stringtoCheck, decimalSeparator)

    'check if there are not characters after decimal point... 
    'if nothin after decimal point, allow this keypress, 
    'if there is already something after decimal point, escape this keypress

    'get length of string after "."
    Dim stringTail As String = ""

    If Not positionOfPoint = 0 Then
        stringTail = Mid(stringtoCheck, positionOfPoint)
        If stringTail.Length > decimalNumber Then
            Return True
        End If
    End If

End Function

回答2:

I have tried this code:

Works Fine Now.. One Digit after decimal point, you may add \d\d to add digits in Regex

 Private Sub TextBox1_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
    If TextBox1.SelectedText.Length = TextBox1.Text.Length Then
        TextBox1.Clear()
    End If
    If Char.IsDigit(e.KeyChar) = True OrElse Char.IsControl(e.KeyChar) = True OrElse e.KeyChar = "."c Then
        If Regex.IsMatch(TextBox1.Text, "\.\d") Then
            'This makes backspace working
            If e.KeyChar = CChar(ChrW(8)) Then
            Else
                e.Handled = True
            End If
        End If
    Else
        e.Handled = True
    End If

End Sub