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LINQ question

Hi, is there a way in LINQ other than using an if statement before the LINQ to get select2 below populated with an empty list? As the code below stands at the moment, it errors at runtime.

            List<string> list1 = new List<string> { "one", "two" };
            var select1 = from l1
                            in list1
                          select "value-" + l1;

            List<string> list2 = null;
            var select2 = from l2
                            in list2
                          select "value-" + l2;

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At the moment I use the code below to overcome the problem. Is this how you have to do it?

            List<string> list2 = null;
            var select2 = from l2
                            in list2 ?? new List<String>()
                          select "value-" + l2;

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Thank you.

kaufmed

That's how I would do it if I *had* to use that code, but I must ask: Why initialize list2 to null if you're just going to refer to it in the subsequent query immediately following?

kaufmed

P.S.

And I must be misunderstanding your goal here, because as it stands, there won't be anything in select2... I'm wondering if you are really wanting this:

var select2 = Enumerable.Empty<string>();

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John Bolter

ASKER

Hi, and thanks.

> Why initialize list2 to null if you're just going to refer to it
> in the subsequent query immediately following?

It is just showing what I want to do without a whole lot of other irrelevant code. The list<string> is actually returned from a method, and I do stuff with it before the LINQ.

ASKER CERTIFIED SOLUTION

kaufmed

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