Comparison of Regex flavours

Question

I wonder if there is a comparison between the features of various regex metacharacters in various implementations.

The sort of thing I am looking for is a table like

Language       Perl    sed
grouping       ( )     \( \)

Languages I am interested in are Perl, Sed Java Javascript

Answer 1

There's a comprehensive comparison page here: Regular Expression Flavor Comparison.

Some languages implement a particular style, so look up your language on that page and determine which column to look at. For example, JavaScript will be under ECMA. For sed it depends on whether you're using UNIX or Linux (from the page):

The sed UNIX tool uses POSIX BRE. Linux usually ships with the GNU implementation, which use "GNU BRE".

Answer 2

A script called txt2regex allows you to build a regex and shows you the syntax for various flavors.

Answer 3

The Wikipedia comparison of regular expression engines chart is comprehensive and easy to understand.

There is also Richard Kettlewell's regexp syntax summary.