Преобразование строки в число с плавающей точкой

 v2 = Convert.ToDouble(TextBox2.Text, CultureInfo.GetCultureInfo("ru-RU"))

Double.TryParse

v2 = Convert.ToDouble(TextBox2.Text.Replace(",","."), CultureInfo.GetCultureInfo("en-US"))

Dim iDouble as Double=CDbl(TextBox1.Text)

Dim iDouble as Double=CType(TextBox1.Text, Double)

Dim txtDouble As String = "2.56"
Dim number As Double = txtDouble.Replace(".", ",")

        Dim separator As String = System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator(0)
        Dim txtDouble As String = "2.56"
        Dim number As Double = Convert.ToDouble(Replace(txtDouble, ".", separator))

        Dim sep As Char = System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator
        For Each d In TextBox1.Text
            If Not Char.IsDigit(d) Then
                'MsgBox("Выражение не является десятичным числом")
                TextBox1.Text = Math.Round(CDec(TextBoxX1.Text.Replace(d, sep)), 2)
            End If
        Next

CDec(TextBox1.Text.Replace(d, sep))

        Dim en, ru As Globalization.CultureInfo
        en = Globalization.CultureInfo.CreateSpecificCulture("en-GB")
        ru = Globalization.CultureInfo.CreateSpecificCulture("ru-RU")
        Dim val#
        Try
            val = Double.Parse(TextBox1.Text, ru)
        Catch ex As FormatException
            val = Double.Parse(TextBox1.Text, en)
        End Try
        TextBox1.Text = val