Exercises, examples and other material relating to training module Q804. This topic is presented on public course Regular Expressions
|Articles and tips on this subject||updated|
|3091||How do regular expressions work / Regular Expression diagrams|
If you want to help yourself work out what a regular expression means, you can draw a regular expression matching flow chart such as this one. I've taken the regular expression .*@.* - a very basic "it might be an email address" filter - and sketched out how the regular expression engine actually matches.
|3090||Matching to a string - what if it matches in many possible ways?|
If you're looking to match and capture part of a string that matches your pattern, you have to be very careful to ensure that you match the correct part of the incoming string. If - for example - I were to ask you what 3 digit numbers the text "I live at 404 and my phone number is 708225" contains, you ...
|2806||Macho matching - do not do it!|
There's something vaguely macho about doing a grand regular expression match to do all your filtering in a single line of code - but being macho may be less than efficient. It may be far better to do two shorter matches, with the first quickly rejecting records which don't need to be handled in detail, ...
|2727||Making a Lua program run more than 10 times faster|
I made an extraordinary claim on Thursday. One of my delegates had written a program that analyzed a huge data file in a Lua script, and it was taking over half an hour to run. "Give me five minutes, and I could have that running in less that five minutes" I claimed.
It was all to do with pattern ...
|1480||Next course - 7th January 2008, Regular Expressions|
Yesterday afternoon ... I finished my training for 2007, and I'm now looking forward to two weeks of days with a different metric. Don't get me wrong - I utterly enjoy the training but all sorts of things have been stacking up to attend to including personal time. So it's not "quiet" but rather "different".
Some modules are available for download
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Topics covered in this module
Compile and match phases.
Saving state and backtracking - why and what is the effect?
Global and "study" matches, Regular Expression objects, etc
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