處理查詢運算式中的例外狀況

class ExceptionsOutsideQuery
{
    static void Main()
    {
        // DO THIS with a datasource that might
        // throw an exception. It is easier to deal with
        // outside of the query expression.
        IEnumerable<int> dataSource;
        try
        {
            dataSource = GetData();
        }
        catch (InvalidOperationException)
        {
            // Handle (or don't handle) the exception 
            // in the way that is appropriate for your application.
            Console.WriteLine("Invalid operation");
            goto Exit;
        }

        // If we get here, it is safe to proceed.
        var query = from i in dataSource
                    select i * i;

        foreach (var i in query)
            Console.WriteLine(i.ToString());

        //Keep the console window open in debug mode
        Exit:
        Console.WriteLine("Press any key to exit");
        Console.ReadKey();
    }

    // A data source that is very likely to throw an exception!
    static IEnumerable<int> GetData()
    {
        throw new InvalidOperationException();
    }
}