Well I think RE's are horribly over used. I think this comes from an unjustified fear about parsers or complete ignorance that they even exist by most programm

Well I think RE's are horribly over used. I think this comes from an unjustified fear about parsers or complete ignorance that they even exist by most programmers. For example lets write a RE to recognize and extract a phone number, here is your spec: http://en.wikipedia.org/wiki/Local_conventions_for_writing_telephone_numbers http://en.wikipedia.org/wiki/Local_conventions_for_writing_t... Have you screamed yet, for example in the US the exact same phone number can be written like so, some of the variants I have seen: (516)-123-4567 1(516)-123-4567 1-516-123-4567 123-4567 old fashioned but valid 1.516.123.4567 now with a parser I can use RE for the simple bits that turn a text stream into bits of data and then hand it off to the to the parser to figure out if it is a good phone number. So the lexer, where the simple RE live, can turn a stream of text into a stream of tokens that the parser can reason about, for my US example above here is the list: 1: a string of digits called NUMBER and what they are 2: a ( called LP 3: a ) called RP 4: a - called DASH 5: a . called DOT Then I can parse the 5 things above to figure out is it a valid phone number in nice readable and maintainable code. Doing the above also makes you much more immune to changes in the RE libs behavior, I have gotten bit by greediness changes in perl before on bug fix releases because I did not follow my above advice. Another benefit is that in 6 months is that you can figure out what you did and so can the next guy