For a non-online version of checking and analysing the structure of regexes, see http://www.weitz.de/regex-coach/ http://www.weitz.de/regex-coach/ It's excelle

For a non-online version of checking and analysing the structure of regexes, see http://www.weitz.de/regex-coach/ http://www.weitz.de/regex-coach/ It's excellent, and together with with regular-expression.info a way to learn regexes that at least worked for me.