Hashtable/Dictionary collisions

Question

Using the standard English letters and underscore only, how many characters can be used at a maximum without causing a potential collision in a hashtable/dictionary.

Answer 1

If your key is a string (e.g., a Dictionary) then it's GetHashCode() will be used. That's a 32bit integer. Hashtable defaults to a 1 key to value load factor and increases the number of buckets to maintain that load factor. So if you do see collisions they should tend to occur around reallocation boundaries (and decrease shortly after reallocation).