You need the put the characters you wish to split on in a character class, which tells the regular expression engine “any of these characters is a match”. For your purposes, this would look like:
Although dashes have special meaning in character classes as a range specifier (ie
[a-z] means the same as
[abcdefghijklmnopqrstuvwxyz]), if you put it as the last thing in the class it is taken to mean a literal dash and does not need to be escaped.
To explain why your pattern didn’t work,
/-./ tells the regular expression engine to match a literal dash character followed by any character (dots are wildcard characters in regular expressions). With “02-25-2010”, it would split each time “-2” is encountered, because the dash matches and the dot matches “2”.