Problem with objects and automatic numbering in VB.NET

22 Jan 2006 5:21 PM

johndevlon

Hi everyone,

I'm having a small problem using objects in VB.NET.

I've created a class "Shop" and one of its properties is a number which
I've named "intNumber" (Integer).

I've created several objects of the class Shop and everythink works
fine. What I'm trying to do is to modify my class in such a manner that
when a create a new object, the property "intNumber" has already a
value. Using a constructor you can do this but I would like to give
each object a different number, starting at 1 or 0, increasing 1 each
time a new object has been created...

The first object has automatically number 1 assigned to "intNumber" ,
the second number 2, etc...

I know this is possible but have forgotten how to do this ...

Many thanks

John

22 Jan 2006 6:18 PM

Jon Skeet [C# MVP]

<johndev***@hotmail.com> wrote:
Show quoteHide quote

> I'm having a small problem using objects in VB.NET.
>
> I've created a class "Shop" and one of its properties is a number which
> I've named "intNumber" (Integer).
>
> I've created several objects of the class Shop and everythink works
> fine. What I'm trying to do is to modify my class in such a manner that
> when a create a new object, the property "intNumber" has already a
> value. Using a constructor you can do this but I would like to give
> each object a different number, starting at 1 or 0, increasing 1 each
> time a new object has been created...
>
> The first object has automatically number 1 assigned to "intNumber" ,
> the second number 2, etc...
>
> I know this is possible but have forgotten how to do this ...

Use a Shared variable to keep track of how many instances have been
created before. Don't forget threading - either acquire a lock while
you're incrementing, or use the Interlocked class.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

22 Jan 2006 7:00 PM

johndevlon

Hi,
Many thanx for the fast responses.

Jon, could you please give a small example ?

John

22 Jan 2006 11:05 PM

Jon Skeet [C# MVP]

<johndev***@hotmail.com> wrote:

> Jon, could you please give a small example ?

Something like this:

Imports System
Imports System.Threading

Class Test

    Shared instancesCreated As Integer

    Dim id As Integer

    Sub New
        id = Interlocked.Increment (instancesCreated)
    End Sub

    Shared Sub Main()

       Dim x0 As New Test
       Dim x1 As New Test
       Dim x2 As New Test
       Dim x3 As New Test

       Console.WriteLine (x0.id)
       Console.WriteLine (x1.id)
       Console.WriteLine (x2.id)
       Console.WriteLine (x3.id)

    End Sub

End Class

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

23 Jan 2006 7:11 AM

TalkUdaiAboutBiz

Hi John,

You must define it as a static member and try working around this.

Regards

Udai.M
Team Leader,Consultant
Chimeratechnologies
Bangalore

Show quoteHide quote

"johndev***@hotmail.com" wrote:

> Hi everyone,
>
> I'm having a small problem using objects in VB.NET.
>
> I've created a class "Shop" and one of its properties is a number which
> I've named "intNumber" (Integer).
>
> I've created several objects of the class Shop and everythink works
> fine. What I'm trying to do is to modify my class in such a manner that
> when a create a new object, the property "intNumber" has already a
> value. Using a constructor you can do this but I would like to give
> each object a different number, starting at 1 or 0, increasing 1 each
> time a new object has been created...
>
> The first object has automatically number 1 assigned to "intNumber" ,
> the second number 2, etc...
>
> I know this is possible but have forgotten how to do this ...
>
> Many thanks
>
> John
>
>