[Webinar] Streamline your web hosting managementRegister Today

x
?
Solved

Generics - List.Exists Method

Posted on 2006-07-04
5
Medium Priority
?
1,602 Views
Last Modified: 2008-03-17
Hello,

I am very new to generics and looking for an example showing how to use the List.Exists delegate. I want to search a particular list to see if an item exists in it.  If the item doesn't exist, I want to add it to another list (I'm trying to test for duplicates).

I'm trying to do something like this (I know the syntax is incorrect.):

foreach (myListItem item in myItemList
{
     if (!returnedItemList.Exists(item) // not sure of syntax here
    {
         newList.Add(item);
    }
}


How would I perform this check using the Predicate delegate?

Thanks!
0
Comment
Question by:marmaxx
  • 3
  • 2
5 Comments
 
LVL 44

Expert Comment

by:bruintje
ID: 17040293
Hi marmaxx,
----------

funny a likewise question was blogged here
http://channel9.msdn.com/ShowPost.aspx?PostID=76961

not sure about it but in that instance the Contains function was needed is that what you need?

foreach (myListItem item in myItemList
{
     if (!returnedItemList.Contains(item)
    {
         newList.Add(item);
    }
}

----------
bruintje
share what you know, learn what you don't
0
 

Author Comment

by:marmaxx
ID: 17040360
Hi bruintje,

No, unfortunately I can't use the Contains method. The program I am working with uses a different implementation of contains (passing in an object reference rather than a value). Of course, I might not be explaining this very well, since I'm only just starting with generics. Either way, I've go to figure out how to do this using Exists, with the Predicate.
0
 
LVL 44

Accepted Solution

by:
bruintje earned 1500 total points
ID: 17040392
that was added later in the same blog entry

2 ways actually, the first one using the predicate delegate

and another one

--
foreach( string s in returnedItemList )
{

    bool found = returnedItemList.Exists( delegate(string t) { return item == t; } );

    if( !found) { newList.Add( item ); }
}
--

hope this helps a bit more
0
 

Author Comment

by:marmaxx
ID: 17043625
Nope, couldn't get the example to work.

What I am trying to do is compare two Lists: List1 and List2. I want to loop through each item of List1 to determine if it exists in List2. If it does, I want to add it to another list. Each of the list items has an ID property, which I need to convert to string, and compare.

I wasn't able to figure out how to do this using the example.
0
 

Author Comment

by:marmaxx
ID: 17146642
I was able to get this to work with a little 'tweak' here and there. Thanks for the help!
0

Featured Post

Get expert help—faster!

Need expert help—fast? Use the Help Bell for personalized assistance getting answers to your important questions.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction This article series is supposed to shed some light on the use of IDisposable and objects that inherit from it. In essence, a more apt title for this article would be: using (IDisposable) {}. I’m just not sure how many people would ge…
High user turnover can cause old/redundant user data to consume valuable space. UserResourceCleanup was developed to address this by automatically deleting user folders when the user account is deleted.
As many of you are aware about Scanpst.exe utility which is owned by Microsoft itself to repair inaccessible or damaged PST files, but the question is do you really think Scanpst.exe is capable to repair all sorts of PST related corruption issues?
Is your organization moving toward a cloud and mobile-first environment? In this transition, your IT department will encounter many challenges, such as navigating how to: Deploy new applications and services to a growing team Accommodate employee…
Suggested Courses
Course of the Month8 days, 7 hours left to enroll

607 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question