Linq discrepancy between C# and VB.Net

03-13-08, 05:59 PM

Chris Dunaway

I use the following the C# Linq expression to find a list of processes
with unique names and it returned the results I
expected. However, curiously, the VB version did not seem to work.
Can anyone correct my VB version so that it returns the same results
as the C# version?

C# version works (new keyword used so data binding will work
correctly):

var uniqueProcs = Process.GetProcesses()
.OrderBy(p => p.ProcessName)
.Select(p => new { p.ProcessName })
.Distinct();

VB version doesn't work (New keyword used so data binding will work
correctly):

Dim uniqueProcs = Process.GetProcesses() _
.OrderBy(Function(p) p.ProcessName) _
.Select(Function(p) New With {p.ProcessName}) _
.Distinct()

When I say that the VB version doesn't work, I mean that it returns a
list, but the duplicates are not removed.

Thanks,

Chris

03-13-08, 06:24 PM

Patrice

In VB you have to use the "key" keyword (don't ask me why ?) :

Dim uniqueProcs = Process.GetProcesses() _
.OrderBy(Function(p) p.ProcessName) _
.Select(Function(p) New With {KEY p.ProcessName}) _
.Distinct()

My personal preference would be to use :

Dim uniqueprocs = From p In Process.GetProcesses _
Order By p.ProcessName _
Select p.ProcessName Distinct

03-13-08, 07:16 PM

Chris Dunaway

On Mar 13, 1:24 pm, "Patrice" <http://www.chez.com/scribe/> wrote:
> In VB you have to use the "key" keyword (don't ask me why ?) :
>
> Dim uniqueProcs = Process.GetProcesses() _
> .OrderBy(Function(p) p.ProcessName) _
> .Select(Function(p) New With {KEY p.ProcessName}) _
> .Distinct()
>
> My personal preference would be to use :
>
> Dim uniqueprocs = From p In Process.GetProcesses _
> Order By p.ProcessName _
> Select p.ProcessName Distinct
>
> --

Yes, so would, but the question originally arose from how to databind
the result to a DataGridView. The query you show won't display
properly in a DataGridView. Instead it has to be changed as so:

Dim uniqueprocs = From p In Process.GetProcesses _
Order By p.ProcessName _
Select New With {Key p.ProcessName}
Distinct

Thanks for the response and the solution.

Chris

03-14-08, 02:10 PM

Nick Hall

"Chris Dunaway" <dunawayc> wrote in message
news:a8a1
> On Mar 13, 1:24 pm, "Patrice" <http://www.chez.com/scribe/> wrote:
>
> Yes, so would, but the question originally arose from how to databind
> the result to a DataGridView. The query you show won't display
> properly in a DataGridView. Instead it has to be changed as so:
>
> Dim uniqueprocs = From p In Process.GetProcesses _
> Order By p.ProcessName _
> Select New With {Key p.ProcessName}
> Distinct
>
> Thanks for the response and the solution.
>
> Chris

Paul Vick has an explanation here for the difference in behaviour: -
http://www.panopticoncentral.net/arc.../11/20566.aspx

Nick Hall

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