CODEWITHSUNDEEP
c#objectarraylist.net-2.0
Leandro Bardelli
Leandro Bardelli

Reputation: 11588

Compare two List<> on C#

My question is like this one: c# list compare

but the only thing to note is this:

I'm using .NET Framework 2.0

So how can I compare two lists on C# framework 2 and return a boolean value if the items are different?

instance == anotherone fails
instance.Equals(anotherone) fails.

Edit:

They are both List

Edit 2

I'm trying to compare if the list values are exactly. I can sort them, np for that. The problem is if the count or the values of the items changes. For example:

List1->Item1 = "A"
List1->Item2 = "B"

List2->Item1 = "B"
List2->Item2 = "A"

//must return true


List1->Item1 = "A"
List1->Item2 = "B"

List2->Item1 = "B"
List2->Item2 = "C"

//must return false

List1->Item1 = "A"
List1->Item2 = "B"

List2->Item1 = "B"
List2->Item2 = "A"
List2->Item3 = "A"

//must return false, etc.

Thanks and kind regards.

Upvotes: 0

Views: 4193

Answers (3)

Greg Finzer
Greg Finzer

Reputation: 7054

Leandro,

You could also use my open source Compare .NET Objects Library. You would set the Config.IgnoreCollectionOrder to true.

https://comparenetobjects.codeplex.com/

[Test]
public void ComparerIgnoreOrderSimpleArraysTest()
{
    var a = new String[] { "A", "E", "F" };
    var b = new String[] { "A", "c", "d", "F" };

    var comparer = new CompareLogic();
    comparer.Config.IgnoreCollectionOrder = true;
    comparer.Config.MaxDifferences = int.MaxValue;

    ComparisonResult result = comparer.Compare(a, b);
    Console.WriteLine(result.DifferencesString);
    Assert.IsTrue(result.Differences.Where(d => d.Object1Value == "E").Count() == 1);
    Assert.IsTrue(result.Differences.Where(d => d.Object2Value == "c").Count() == 1);
    Assert.IsTrue(result.Differences.Where(d => d.Object2Value == "d").Count() == 1);

}

Upvotes: 1

jason
jason

Reputation: 241651

For the question that you link to on computing the intersection, you would need to implement your own version of Intersect. This should get you started:

List<T> Intersect<T>(List<T> first, List<T> second) {
    Dictionary<T, T> potential = new Dictionary<T, T>();
    foreach (var item in first) {
        potential.Add(item, item);
    }
    List<T> intersection = new List<T>();
    foreach (var item in second) {
        if (potential.Remove(item)) {
            intersection.Add(item);
        }
    }
    return intersection;
}

To handle if they have the same items with the same frequency:

bool AreSameAsMultiSets(List<T> first, List<T> second) {
    Dictionary<T, int> counts = new Dictionary<T, int>();     
    foreach (var item in first) {
        if (!counts.ContainsKey(item)) {
            counts.Add(item, 0);
        }
        counts[item] = counts[item] + 1;
    }
    foreach (var item in second) {
        if (!counts.ContainsKey(item)) {
            return false;
        }
        counts[item] = counts[item] - 1;
    }
    foreach (var entry in counts) {
        if (entry.Value != 0) {
            return false;
        }
    }
    return true;
}

You should probably add some error-handling to the above (first is not null, second is not null). Note that you can't use HashSet<T> since you're in .NET 2.0.

Upvotes: 5

Guffa
Guffa

Reputation: 700422

If you want to check if the lists contain identical items (i.e. the same items in the same order):

public static bool ListsEqual<T>(List<T> list1, List<T> list2) {
  if (list1.Count != list2.Count) return false;
  for (int i = 0; i < list1.Count; i++) {
    if (list1[i] != list2[i]) return false;
  }
  return true;
}

Upvotes: 4

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