How do I use more than nine backreferences in Notepad++ regexp?

Question

If I use a long regular expression in Notepad++, i.e.:

^([^ ]+) ([^ ]+) ([^ ]+) (\[.*?\]) (".*?") (".*?") (".*?") (".*?") (\d+) (\d+) (\d+)$

(this is for turning an Apache log lines from space-separated to tab-separated)

then I can't successfully use more than nine backreferences for replacing, as \10 yields the content of the first captured group plus a literal "0".

I tried with $10, but that gives the same result.

use curly brackets: `${10}` – Casimir et Hippolyte Mar 15 '16 at 11:51 — Casimir et Hippolyte, Mar 15 '16 at 11:51

Lucas Trzesniewski · Accepted Answer · 2016-03-15T11:56:29.710

10

You can use curly braces for this:

${10}

For reference, Notepad++ uses boost::regex, and you can find its substitution pattern docs here: Boost-Extended Format String Syntax. This replacement mode allows for more complex expressions (like conditionals and common Perl placeholders) in the replacement pattern.

edited Mar 15 '16 at 11:56

answered Mar 15 '16 at 11:51

Lucas Trzesniewski

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Does this means I can use it the same for javascript regexp? – Rahul Mar 15 '16 at 11:53
2

@Rahul: No, JS "understands" `$10` (it is rather smart in disambiguating backreference IDs). – Wiktor Stribiżew Mar 15 '16 at 11:54
@Rahul JavaScript has its own regex spec, but in JS you can simply use a callback function for replacements, so the problem is non-existent. – Lucas Trzesniewski Mar 15 '16 at 11:55
Thanks for the additional documentation! – watery Mar 15 '16 at 13:58

CinCout · Answer 2 · 2016-03-15T11:59:47.317

2

Just use the curly braces:

${10}

This will ensure that the 10th capturing group is being referred, and not the 1st group followed by zero.

edited Mar 15 '16 at 11:59

answered Mar 15 '16 at 11:52

CinCout

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How do I use more than nine backreferences in Notepad++ regexp?

2 Answers2