Confusion with C# declaration

Question

what does this declaration mean :

int ? value

and what is he's equivalent on VB.NET .

Thanks

Cut the OP some slack - have you tried googling on "int?" - certainly nothing related on the first page of results. — Dave Doknjas, Jun 11 '13 at 14:53
@DaveDoknjas: Searching for "C# int?" gives plenty of good results. Searching for "C# specification" and then searching the specification would also have worked. — Eric Lippert, Jun 11 '13 at 15:39

score 3 · Answer 1 · answered Jun 11 '13 at 14:06

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It means that this integer is nullable, you can assign a null value to it... try to do that with an integer without a ? and it with throw an exception

Edit: Oh and VB.net will declare a nullable int like this

    Dim i As Integer?

answered Jun 11 '13 at 14:06

Mikey Mouse

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Uh, I'm pretty sure that's invalid syntax for a nullable `int`. – Mike Perrenoud Jun 11 '13 at 14:07
Could be, it's been a while since I used vb.net, one moment I'll try it out on LinqPad – Mikey Mouse Jun 11 '13 at 14:08
@MichaelPerrenoud It runs ok in LinqPad, and I can assign Nothing to it, although the Nullable(Of Integer) seems to be the more used syntax – Mikey Mouse Jun 11 '13 at 14:12
Alright friend, +1 for you! – Mike Perrenoud Jun 11 '13 at 14:14
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@MichaelPerrenoud Woohoo, that puts me over 1000, you're my hero! – Mikey Mouse Jun 11 '13 at 14:15
I remember the feeling. I remember then after that it was when I broke 10K. – Mike Perrenoud Jun 11 '13 at 14:17
VB supports the ? syntax for Nullable types. See section 7.1.1 of the VB Spec. – Chris Dunaway Jun 11 '13 at 14:18

score 2 · Answer 2 · answered Jun 11 '13 at 14:07

2

int? is short for Nullable<int>. The VB.NET equivalent is Nullable(Of Integer).

answered Jun 11 '13 at 14:07

wgraham

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VB.Net also supports the ? notation for nullable types. (VB 10) – Chris Dunaway – Chris Dunaway Jun 11 '13 at 15:17

score 2 · Answer 3 · answered Jun 11 '13 at 14:07

2

It's declaring a new instance of the Nullable<Int32> type. int? is just a shorter way of writing it.

Further Reading

Nullable Types (C# Programming Guide)

answered Jun 11 '13 at 14:07

p.s.w.g

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Tom Studee · Answer 4 · 2013-06-11T14:25:17.813

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It is a Nullable<int> data type.

The equivalent in vb is Dim value as Nullable(Of Integer) or Dim value as Integer?

edited Jun 11 '13 at 14:25

answered Jun 11 '13 at 14:07

Tom Studee

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score 2 · Answer 5 · answered Jun 11 '13 at 14:07

2

It's syntatic sugar for

Nullable<int> value

meaning that it can have a null value

answered Jun 11 '13 at 14:07

daz-fuller

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score 1 · Answer 6 · answered Jun 11 '13 at 14:08

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Nullable value types. It means that the variable can contain a null value. For more details both for VB.NET and C#.NET view this link http://msdn.microsoft.com/en-us/library/ms235245.aspx

answered Jun 11 '13 at 14:08

Mez

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score 1 · Answer 7 · answered Jun 11 '13 at 14:08

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It a nullable int and is a short term of

Nullable<int> value;

In VB.net you would write

dim value as Nullable( of Integer )

See this msdn page for more details and examples.

answered Jun 11 '13 at 14:08

Matten

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VB.Net also supports the ? notation for nullable types. (VB 10) – Chris Dunaway Jun 11 '13 at 15:17

score 1 · Answer 8 · answered Jun 11 '13 at 14:08

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Try to read about nullable on msdn (http://msdn.microsoft.com/en-us/library/b3h38hb0.aspx)

answered Jun 11 '13 at 14:08

Frank59

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score 1 · Answer 9 · answered Jun 11 '13 at 14:09

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The question mark refers to nullable type in C#. You can try using Nullable (Of Integer) in VB.NET.

answered Jun 11 '13 at 14:09

Ispep Aloc

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Confusion with C# declaration

9 Answers9