Problem with objects and automatic numbering in VB.NET

[johndevlon@hotmail.com]

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

[Patrik Löwendahl [C# MVP]]

Re: Problem with objects and automatic numbering in VB.NET

Hello john

Use a static variable to hold the last number:


public class Shop {
private static int nextNumber = 0;
private int number;

public int Number {
get { retun this.number; }
}

public Shop() {
this.number = nextNumber;
nextNumber++;
}

}


--
Patrik Löwendahl [C# MVP]

http://www.lowendahl.net

http://www.cornerstone.se

[color=blue]
> 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
>[/color]

[Jon Skeet [C# MVP]]

Re: Problem with objects and automatic numbering in VB.NET

<johndevlon@hot mail.com> wrote:[color=blue]
> 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 ...[/color]

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

[Patrik Löwendahl [C# MVP]]

Re: Problem with objects and automatic numbering in VB.NET

Hello Patrik,

LOL sorry, read johns post. Shared is the correct term in VB.NET. A bit to
quick there.


--
Patrik Löwendahl [C# MVP]

http://www.lowendahl.net

http://www.cornerstone.se

[color=blue]
> Hello john
>
> Use a static variable to hold the last number:
>
> public class Shop {
> private static int nextNumber = 0;
> private int number;
> public int Number {
> get { retun this.number; }
> }
> public Shop() {
> this.number = nextNumber;
> nextNumber++;
> }
> }
>
> --
> Patrik Löwendahl [C# MVP]
> http://www.lowendahl.net
> http://www.cornerstone.se[color=green]
>> 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
>>[/color][/color]

[johndevlon@hotmail.com]

Re: Problem with objects and automatic numbering in VB.NET


Hi,
Many thanx for the fast responses.

Jon, could you please give a small example ?

John

[Jon Skeet [C# MVP]]

Re: Problem with objects and automatic numbering in VB.NET

<johndevlon@hot mail.com> wrote:[color=blue]
> Jon, could you please give a small example ?[/color]

Something like this:

Imports System
Imports System.Threadin g

Class Test

Shared instancesCreate d As Integer

Dim id As Integer


Sub New
id = Interlocked.Inc rement (instancesCreat ed)
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.WriteLi ne (x0.id)
Console.WriteLi ne (x1.id)
Console.WriteLi ne (x2.id)
Console.WriteLi ne (x3.id)

End Sub


End Class

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

[TalkUdaiAboutBiz]

RE: Problem with objects and automatic numbering in VB.NET

Hi John,

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

Regards

Udai.M
Team Leader,Consulta nt
Chimeratechnolo gies
Bangalore


"johndevlon@hot mail.com" wrote:
[color=blue]
> 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
>
>[/color]