C# Exception causes my form to close

Question

When I throw a FormatException, the form always seems to close. Is there a way that the form doesn't close so I can do actions on the form?

Example:

    int postcodeNumeriek = 0;
    if (int.TryParse(postcode.Text, out postcodeNumeriek) == false)
    {
        throw new FormatException("De postcode heeft een verkeerd formaat");
    }

    cmd.Parameters.AddWithValue("@naam", familienaam.Text);
    cmd.Parameters.AddWithValue("@voornaam", voornaam.Text);
    cmd.Parameters.AddWithValue("@straat", straat.Text);
    cmd.Parameters.AddWithValue("@nummer", nummer.Text);
    cmd.Parameters.AddWithValue("@bus", bus.Text);
    cmd.Parameters.AddWithValue("@postcode", postcode.Text);
    cmd.Parameters.AddWithValue("@gemeente", gemeente.Text);
    cmd.Parameters.AddWithValue("@telefoonnummer", telefoonnummer.Text);
    cmd.Parameters.AddWithValue("@btwnummer", btwNummer.Text);
    cmd.Parameters.AddWithValue("@nieuwsbrief", nieuwsbrief.Checked);
    cmd.Parameters.AddWithValue("@emailadres", emailAdres.Text);
    cmd.Parameters.AddWithValue("@klantnummer", klantID);

    cmd.ExecuteNonQuery();

    cmd = new SqlCeCommand("UPDATE Klanten SET Actief=0 WHERE ID='" + recordID + "'", Klantenbeheer.HuidigeDatabaseVerbinding);
    cmd.ExecuteNonQuery();
}
catch (FormatException e)
{
    postcode.Focus();
}

In this example, I want my postal code to generate an exception when it is formatted incorrectly. When this happens, the form just closes so the postcode.Focus(); doesn't get executed.

Maybe it does but it's not visible.

Answer 1

Ik denk dat het handiger is als je die FormatException weg haalt. En de textbox bijvoorbeeld vult met wat tekst waar in staat dat het formaat niet klopt.

I think it would be better to remove the FormatException. The tryparse is fine. But just fill the textbox with some info.

int postcodeNumeriek = 0;

if (int.TryParse(postcode.Text, out postcodeNumeriek) == false)
{
    postcode.Text ="format postalcode incorrect";
}

and in these cases its always good to use the Try statement.