Passing nullable string

[tshad]

I have a function that I want to pass data that gets data from my Sql
Database, so the value can be null but I get an error if I try it.

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

This works:

public void test(int? x){}

But this doesn't:

public void test(string? x){}

How can I get this to work?

I am using a dbReader and putting the data into a string or int or double
and then passing it to its functions.

Can you pass just a row of the dbReader?

Thanks,

Tom

 

[Arne Vajhøj]

I have a function that I want to pass data that gets data from my Sql
Database, so the value can be null but I get an error if I try it.

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

This works:

public void test(int? x){}

But this doesn't:

public void test(string? x){}

string is a reference type and is nullable, so just:

public void test(string x){}

will allow you to use null as parameter.

Arne

 

[tshad]

Makes sense.

Thanks,

Tom

That's a big hint to you. The error strongly implies that String is _not_
"non-nullable", which means it's already nullable. It would be pointless
to wrap String in Nullable<T>, since String itself (being a reference
type) is automatically "nullable".

Just use the String reference directly.

Pete