Check if two Lists are equal

Vote count:

4

I have a class as follows:

public class Tag {
  public Int32 Id { get; set; }
  public String Name { get; set; }
}

And I have two lists of tag:

List<Tag> tags1;
List<Tag> tags2;

I used Linq's select to get the Ids of each tags list. And then:

  List<Int32> ids1 = new List<Int32> { 1, 2, 3, 4 };

  List<Int32> ids2 = new List<Int32> { 1, 2, 3, 4 };

  List<Int32> ids3 = new List<Int32> { 2, 1, 3, 4 };

  List<Int32> ids4 = new List<Int32> { 1, 2, 3, 5 };

  List<Int32> ids5 = new List<Int32> { 1, 1, 3, 4 };

ids1 should be equal to ids2 and ids3 ... Both have the same numbers.

ids1 should not be equal to ids4 and to ids5 ...

I tried the following:

  var a = ints1.Equals(ints2);

  var b = ints1.Equals(ints3);

But both give me false.

What is the fastest way to check if the lists of tags are equal?

edited 37 secs ago

Tijesunimi

2,930

asked 3 mins ago

MDMoura

1,023

2 Answers

Vote count:

10

List<T> equality does not check them element-by-element. You can use LINQ's SequenceEqual method for that:

var a = ints1.SequenceEqual(ints2);

answered 2 mins ago

dasblinkenlight

224k

Vote count:

8

Use SequenceEqual to check for sequence equality.

 var a = ints1.SequenceEqual(ints2);

Or if you don't care about elements order use All method:

var a = ints1.All(ints2.Contains);

answered 1 min ago

Selman22

14.9k