The regular expressions guides
Wikipedia defines regular expressions like this: In computing, a regular expression, also referred to as regex or regexp, provides a concise and flexible means for matching strings of text, such as particular characters, words, or patterns of characters. A regular expression is written in a formal language that can be interpreted by a regular expression processor, a program that either serves as a parser generator or examines text and identifies parts that match the provided specification.
Regular expressions - theory
- Perldoc page about regular expressions
- Guide to regular expressions
- Parsing HTML using Regular Expressions - but i don't think it is good idea
- How to design regular expressions parser - tech paper