How do I fix the code below to validate?

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The type 'string' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'Nullable<t>'

What I have tried:

I tried setting the parameter and got the message above from

C#

String? prob = record.GetValueString(_Prbblty);

Posted 17-May-21 6:57am

Leon Griffin

Updated 17-May-21 8:41am

RickZeeland

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OriginalGriff · Answer 1 · 2021-05-17T08:35:00

String is not a value type - it's a reference type which means it can contain null values already.

You can only declare nullable variables if they are value types (int, float, double, ... or struct rather than class based).

That's what the error message is saying, but in a roundabout way because of how it is implemented as a "Nullable<T>" with syntactic sugar you type as "T?"

Gerry Schmitz · Answer 2 · 2021-05-17T08:41:00

Solution 2

All reference types are nullable; String is considered a reference type; you can already assign null to a string.

At some point, string? will mean that you want a nullable "reference" to a string; and not an actual null string.

Posted 17-May-21 8:41am

Gerry Schmitz

How do I fix the code below to validate?

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How do I fix the code below to validate?

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