C#

public class SwitchOnDTOrdinal
{
    public SwitchOnDTOrdinal(DataTable table)
    {
        TheTable =  table;

        validColumnNames = table.Columns
            .Cast<DataColumn>()
            .Select(col => col.ColumnName)
            .ToList();
    }

    private List<string> validColumnNames;

    private DataTable TheTable;

    public void SwitchA(string cname)
    {
        if (! validColumnNames.Contains(cname))
        {
            throw new ArgumentException(@"{cname} is not a valid column name");
        }

        switch(TheTable.Columns[cname].Ordinal)
        {
            case 0:
                break;
            case 1:
                break;
            case 2:
                break;
            case 3:
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }
    }
}

HoaiNTT0610 wrote:

Look forward to the help of all

When a form is displayed as a modal dialog box, clicking the Close button (the button with an X at the upper-right corner of the form) causes the form to be hidden and the DialogResult property to be set to DialogResult.Cancel. Unlike non-modal forms, the Close method is not called by the .NET Framework when the user clicks the close form button of a dialog box or sets the value of the DialogResult property. Instead the form is hidden and can be shown again without creating a new instance of the dialog box. Because a form displayed as a dialog box is hidden instead of closed, you must call the Dispose method of the form when the form is no longer needed by your application.