How to determine if two generic type values are equal?

Question

Update* I am so sorry... my sample code contained an error which resulted in a lot of answers I didn\'t understand. In stead of

Console.WriteLin         


        

Answer 1

Your code looks fine. The problem here is that StringBuilder has a confusing set of Equals that are contradictory. In particular, Equals(StringBuilder) disagrees with Equals(object), even when the object is a StringBuilder.

All that EqualityComparer needs is a sane Equals(object) implementation. The interface (IEquatable) is optional. Unfortunately StringBuilder doesn't have this (at least, by comparison to Equals(StringBuilder), which your third test is using).

But in general, the advice is: use EqualityComparer; this supports:

• nullable-of-T with standard "lifted" rules
• IEquatable-of-T
• object.Equals