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for each where

Is there a way in vb.net select all elements from a for each statement using a where?
I am not a fan of linq for speed purposes.
It is for a game type program so speed is critical.

I want to iterate through only some elements of a list . Those elements meet some condition.
Like iterate through a list of objects where some property is set to false.

I can use a for each and and if statement currently but I am after a better way.

For Each pt In Mpl
If pt.direction = missileType Then
...

Wayne Taylor (webtubbs)

The only way to do that is with LINQ. Dim pts = From pt In Mpl Where pt.Direction = missleType For Each pt In pts '''' NextWayne

Mike Tomlinson

You can use the List.FindAll() method:
http://msdn.microsoft.com/en-us/library/fh1w7y8z.aspx

Really not sure if it is "better" though...just different...

Made up example:

Public Class Form1

    Private Const missileType As Integer = 0

    Private Class Something
        Public direction As Integer
    End Class

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim Mpl As New List(Of Something)

        ' ...

        For Each pt In Mpl.FindAll(AddressOf FindMissiles)
            ' ...
        Next
    End Sub

    Private Function FindMissiles(ByVal pt As Something) As Boolean
        Return pt.direction = missileType
        ' ... obviously a more complicted match algorithm could be used in here! ...
    End Function

End Class

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HainKurt

what about creating a dynamic datatable, put elements into it (maybe you already getting values from db, in this case you may have a datatable already)
then you can use rowfilter property of datatable.defaultview.rowfilter="id > 10 and id < 20"

--> http://msdn.microsoft.com/en-us/library/system.data.dataview.rowfilter.aspx

jagguy

ASKER

thanks for the replies.

actually it looks worse with all these extra functions and I am wooried about speed as well, database no way and MSDN examples dont always clarify things. Who wites MSDN stuff and does it get proof read for simplicity?

Gururaj Badam

I'm a C# guy, pardon my syntax.

For Each pt In Mpl.Where pt => pt.direction = missileType

this will only iterate elements matching your where condition. I don't know why you feel LINQ will slow down your processing when it's actually design gain performance.

jagguy

ASKER

i havent read anywhere Liunq speeds up performance and have only heard it slows things down because of its design.

Could you show me any article where it says iterating through a list of data using linq is quicker ( or no slwere)than using an if condition .

ASKER CERTIFIED SOLUTION

Gururaj Badam

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