List.FindAll question (new to .net 2.0) please help !!!! URGENT !!!

List.FindAll question (new to .net 2.0) please help !!!! URGENT !!!

• Ken Sykora7765

  here's one way to do it (i typed this code directly into the post, so the syntax may not be exactly right):
  
  Public Sub FindInList(lst As List(Of String), find As String) As String()
      toFind = find
      Return lst.FindAll(AddressOf IsMatch)
  End Sub
  
  Dim toFind As String
  Public Function IsMatch(compare As String) As Boolean
      Return compare = toFind
  End Function
  
  
  
  

• tracy97214

  Is the list class you're using the System.Generic.List(of T) class This is a part of the new generics feature. This feature was designed for a different scenario than dynamically assigned variables. And should be thought as separate. Specifically, when searching dynamically typed variables, there's a huge speed penalty since the type's members must be bound when running the code instead of during compilation.

  Generics are meant to be used to create fast highly optimized "generic" libraries which are then customized by the user by specifying the type when creating instances of the variables. Think of Generics as a hacking the language for speed :)

  ms-help://MS.VSCC.v80/MS.MSDN.v80/MS.VisualStudio.v80.en/dv_vbalr/html/89f771d9-ecbb-4737-88b8-116b63c6cf4d.htm

  When using the Generics class List(of T) the user gives up a little flexibility in assigning the variable types so they can get more speed.

  Okay, if you just want the code to work, and are trying to put different types of data into the a List, you can use the old "Object" type for flexibilty, but you're going to sacrifice speed. The following code will work, but it's ugly and will not be performant.

  Imports System.drawing

  Module mod1

  Sub main()

  ' To find the first Point structure for which X > 200 a delegate

  ' that represents the GreaterThan200 method to the Shared

  ' FindAll method of the collection class.

  Dim Cltn As New Generic.List(Of Object)

  Cltn.Add(New Point(100, 200))

  Cltn.Add(New Point(150, 250))

  Cltn.Add(New Point(250, 275))

  'add a collection element of a very different type.

  Cltn.Add("string")

  'Get Point results

  Dim results As Object = Cltn.FindAll(AddressOf PointGreaterThan200)

  For Each p As Object In results

  MsgBox(p.ToString)

  Next

  End Sub

  ' This method implements the test condition for the FindAll

  ' method.

  Private Function PointGreaterThan200(ByVal p As Object) As Boolean

  Try

  If p.X > 200 Then

  Return True

  Else

  Return False

  End If

  Catch ex As MissingMemberException

  'If the type passed is does not have a member "X" it will receive an MissingMemberException.

  Return False

  End Try

  End Function

  End Module

  
  
  
• List.FindAll question (new to .net 2.0) please help !!!! URGENT !!!