---

            try
            {
                double val = double.Parse(inputTextBox.Text);
 
                double inMeters = 0;
                if (inCm.Checked) inMeters = val / 100.0;
                else if (inM.Checked) inMeters = val;
                else if (inInch.Checked) inMeters = val * 0.0254;
                else if (inFoot.Checked) inMeters = val * 0.3048;
                else if (inYard.Checked) inMeters = val * 0.9144;
 
                double result = 0;
                if (outCm.Checked) result = inMeters * 100.0;
                else if (outM.Checked) result = inMeters;
                else if (outInch.Checked) result = inMeters / 0.0254;
                else if (outFoot.Checked) result = inMeters / 0.3048;
                else if (outYard.Checked) result = inMeters / 0.9144;
 
                outputTextBox.Text = result.ToString("F4");
            }
            catch
            {
                outputTextBox.Text = "";
                MessageBox.Show("Некорректный ввод исходных данных", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Error);
                inputTextBox.Text = "";
            }