"object is null" expression gives an error

Question

I have the following code:

public static class ItemsHelper
{
    public static object product
    {
        get
        {
            return HttpContext.Current.Items["product"];
        }
        set
        {
            HttpContext.Current.Items["product"] = value;
        }
    }
}

And then, in a function, I have the following expression:

if (ItemsHelper.product is null) return false;

I tested in visual studio 2017 and it works fine, but i tested in two different computers that runs visual studio 2015 and it retrieves the following error:

type expected )

Any one have an idea why this is happening?

`is null` is a C# 7 feature, of course it is absent in VS 2015 — Andrey, Oct 17 '17 at 08:57
@Sentry I could, but I'm trying to understand why this is happening — Ricardo Rocha, Oct 17 '17 at 09:00
Detailed explanation [here](https://stackoverflow.com/a/43295208/3214843). — Manfred Radlwimmer, Oct 17 '17 at 09:03
And [why you shouldn't use it instead of `== null`](https://stackoverflow.com/a/45332827/3214843) — Manfred Radlwimmer, Oct 17 '17 at 09:06

henrikmerlander · Accepted Answer · 2018-03-28T10:25:03.800

14

is null is a C# 7 feature. You would need a C# 7 compatible compiler to make your code compile.

Visual Studio 2017 ships with a compatible one but for Visual Studio 2015 you need to update. Check this question for instructions on how to update: How to use c#7 with Visual Studio 2015?.

edited Mar 28 '18 at 10:25

answered Oct 17 '17 at 08:57

henrikmerlander

1,554
13
20

2

The `is` keyword is not a C# 7 feature, just the new usage of `is` for pattern matching. – BJ Myers Mar 27 '18 at 17:59

"object is null" expression gives an error

1 Answers1