Computer Science Canada [Regex-tut] Non-Greedy Matches |
| Author: | wtd [ Sun Nov 14, 2004 12:03 am ] | ||||||||
| Post subject: | [Regex-tut] Non-Greedy Matches | ||||||||
Recap In the previous installments, dealing with negative sets, I used:
To match the contents of a quoted string, where those contents didn't include the quote character itself. I used the above rather than:
Because:
Matches any chatacter zero or more times, and would have matched the quote as well. Why was that necessary? After all, I had specified that the string to be matched should end with a quote. The match should have been complete when it found a quote to match the first one. But it didn't, and it didn't stop because * is "greedy" (+ also behaves this way). If there's another quote, it'll fly right past the one where we would have expected it to stop. A quick fix To fix this, we either have to specify that the string being matched cannot contain a matching quote, which we did, quite successfully, but at the cost of making the regex more complex, or, we simply change the behavior of the * and make it "non-greedy". Following the * (or +) with a question mark will do the trick. In keeping with regex tradition, it's very short.
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