Check if two collections are equal

Question

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Is there a built-in method to compare collections in C#?
Comparing two collections for equality

I have tow collections that i want to check to see if the values contained within are not eqaul.

   SearchResultCollection Users1 = ds1.FindAll();
   SearchResultCollection Users2 = ds2.FindAll();

Next i use 2 foreach loops to iterate through and then assign the variables.

foreach (SearchResult users in Users1)
{
   string ManagerID = users.Properties["OrgUnitManagerName"][0].ToString();
   string subGroup = users.Properties["EmployeeSubGroup"][0].ToString();
   string cn = users.Properties["cn"][0].ToString();

   foreach (SearchResult user in Users2)
   {
     string uid = absaUser.Properties["uid"][0].ToString();
   }
}

What i want to do is: check which users from User1 that do not exixt in user2 and print out that list.

if(cn != uid)
  {
  }

This doesnt seem to work. Any Ideas?

Related thread - http://stackoverflow.com/questions/43500/is-there-a-built-in-method-to-compare-collections-in-c — KV Prajapati, Oct 10 '11 at 14:57

score 3 · Answer 1 · answered Oct 10 '11 at 14:57

Check they both have the same number of records, bail out if not
Do an list1.Except(list2) - if there are any results, bail out

Else - success, they match

Note: this uses the LINQ extension method Except, see here: http://msdn.microsoft.com/en-us/library/bb300779.aspx . Simply put, list1.Except(list2) gives you all items in list1, except those in list2.

The objects will need to implement Equals to compare equality correctly.

Yahia · Answer 2 · 2011-10-10T15:08:28.817

2

use

bool AreIdentical = (Users1.Count == Users2.Count ) && (Users1.Except (Users2).Count() == 0) && (Users2.Except (Users1).Count() == 0);

EDIT - as per comments:

To just get User in User1 and not in User2 use:

var In1ButNotIn2 = Users1.Except (Users2);

edited Oct 10 '11 at 15:08

answered Oct 10 '11 at 14:59

Yahia

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"What i want to do is: check which users from User1 that do not exixt in user2 and print out that list." – Kieren Johnstone Oct 10 '11 at 15:06
Ok so basically what my answer says, but 5 minutes later. OK – Kieren Johnstone Oct 10 '11 at 15:10

Check if two collections are equal

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