mono string hash code collisions
After reading the following blog post by David R. MacIver about hash code collisions in java strings: For reasons you either know about by now or don’t care about, I was curious as to how well String’s hashCode was distributed (I suspected the answer was “not very”). I ran a few quick experiments to verify this. For your amusement, here is a list of all hash collisions between alphanumeric strings of size 2: http://www.drmaciver.com/collisions.txt and here is a list of all which don’t collide with any others http://www.drmaciver.com/noncolliding.txt Some statistics: There are 3844 alphanumeric strings of size 2. Of these 3570 collide with at least one other string. That is, 274 of these strings (or about 7% of them) *don’t* collide with something else. Oh well. It’s a good thing no one would be stupid enough to rely on hashCode to distinguish the contents of two objects. I tested things with .NET 3.5 and MONO 1.9.1 on a 32-bit Windows Vista: running on .NET 3.5: 3844 two-char string