Why SequenceEqual for List returns false?

Question

Hi I have some problems with sequenceEqual when I have situation like this: ``` Sentence s1 = new Sentence { Text = "Hi", Order = 1 }; Sentence s2 = new Sentence { Text = "Hello", Order = 2 }; List list1 = new List { s1, s2 }; List list2 = new List { s1, s2 }; ``` and this works fine ``` bool equal = list1.SequenceEqual(list2); ``` and returns `true`; but when I have some method which returns `List` for example: ``` public List Getall() { Sentence s1 = new Sentence { Text = "Hi", Order = 1 }; Sentence s2 = new Sentence { Text = "Hello", Order = 2 }; return new List { s1, s2 }; } ``` and use it like this: ``` List list1 = Getall(); List list2 = Getall(); ``` and then simply, check it ``` bool equal = list1.SequenceEqual(list2); ``` it returns 'false', please tell me why? and how to make it work?

Accepted Answer

Your problem is that one `new Sentence { Text = "Hi", Order = 1 }` is not equal to another `new Sentence { Text = "Hi", Order = 1 }`. Although the contents are the same, you have two separate objects, and unless you've designed your class otherwise they are not equal to each other unless they are literally the same objects (as in your first example).

Your `Sentence` class needs to override `Equals` and `GetHashCode`, at the very least, at which point your `SequenceEquals` should work again.

Why SequenceEqual for List<T> returns false?

Solution

Problem