Computer Science Canada [Regex-tut] Capturing Groups: Inside the Regex |
| Author: | wtd [ Sat Nov 13, 2004 10:50 pm ] | ||||||||
| Post subject: | [Regex-tut] Capturing Groups: Inside the Regex | ||||||||
Recap Groups surrounded by parentheses remember what they matched and store it in a global variable. This is great, but... What if I want to figure out what a group matched before I'm done matching? Variables like $1, $2, $3, etc. reflect whatever the expression actually matched. It shouldn't be too surprising that someone figured out a way to do something similar in the regex. Let's say we want to match a string between two quotes. We want to allow either single or double quotes, but the key is that they have to match. So, we create an expression to match a single or double quote, and then a bunch of characters. Note: the "." character means essentially "anything".
But, how do I figure out which of the two quotes was matched? Simple, put parentheses around that too.
Now, I need to match that same character at the end of the expression. A backslash followed by the number of the matching parens will work.
And putting it all together:
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