TextBox validation to check range

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Hi,
I want to check whether the give value in textbox is in range or not.I want to check it on focus lost. I have written following code but it give error which say incorrect input string

Thanks In Advance

C#

private void txtbx_Capcity_LostFocus(object sender, RoutedEventArgs e)
        {
            double txtbx = Convert.ToDouble(txtbx_Capcity.Text);
            if (txtbx > 30)
            {
                txtbx_Capcity.Text = "0";
                MessageBox.Show("Out Of Range");
                txtbx_Capcity.Focus();
            }

            else
            {
                txtbx = Convert.ToDouble(txtbx_Capcity.Text);
                txtbx_Capcity.Text = Math.Round(txtbx, 2).ToString();
            }
            e.Handled = true;
        }

Posted 29-Jan-13 19:43pm

Swapnil Girme

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_Maxxx_ · Accepted Answer · 2013-01-29T19:48:00

Solution 1

If the text isn't in a format that can be converted to a double then the Convert.ToDouble will throw an exception - so you rpobably want to catch that exception and tell the user.

See the docco here[^] which gives examples of catching the exception.

Posted 29-Jan-13 19:48pm

_Maxxx_