Remove all character except numbers and decimals?

I want to know if there is an easy and short way to remove all characters except for numbers and decimals from a string. Either that or have a textbox that will only except numbers and decimals, but not a masked textbox.

Here is one way using LINQ.

vb.net Code:

Dim nums = From c In TextBox1.Text _
    Where Char.IsDigit(c) OrElse c = "." _
    Select num = c.ToString
TextBox1.Text = Join(nums.ToArray, "")

You may put this in the TextChanged event, with whatever customization you need, if you do not want this textbox to accept anything else.

Assuming you only want valid decimals, this would be a better approach:

vb.net Code:

Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
    If sender.Text <> String.Empty Then
        Dim TypedNumber As String = sender.Text
        Dim NumberRegex As String = "^[0-9]+\.?[0-9]*$"
        If Not System.Text.RegularExpressions.Regex.Match(TypedNumber, NumberRegex).Success Then
            sender.Text = sender.Text.Remove(sender.Text.Length - 1, 1)
            sender.SelectionStart = sender.Text.Length
        End If
    End If
End Sub

Edit: This would require decimals less than 1 to be typed as "0.5" instead of ".5". If that's a problem just change NumberRegex to "^[0-9]*\.?[0-9]*$"