Word boundary in regexp

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Word boundary in regexp by ikegami (Patriarch) on Jan 25, 2012 at 21:48 UTC
`\b` [download] is equivalent to `(?:(?<=\w)(?!\w)\|(?<!\w)(?=\w))` [download] If you want to include "-" as a word character, just change `\w` to `[\w-]`. `(?:(?<=[\w-])(?![\w-])\|(?<![\w-])(?=[\w-]))` [download] All together, that gives `my $my_slash_b = qr/(?:(?<=[\w-])(?![\w-])\|(?<![\w-])(?=[\w-]))/; /$my_slash_b$check$my_slash_b/` [download] But since you "know" that `$check` starts and ends with a word character, the above simplifies to `/(?<![\w-])$check(?![\w-])/` [download] If you wanted to go further and count any non-whitepspace as word characters, you're left with `my $my_slash_b = qr/(?:(?<=\S)(?!\S)\|(?<!\S)(?=\S))/; /$my_slash_b$check$my_slash_b/` [download] and thus `/(?<!\S)$check(?!\S)/` [download]	[reply] [d/l] [select]
Re: Word boundary in regexp by Eliya (Vicar) on Jan 25, 2012 at 21:30 UTC
See also Defining Characters in Word Boundary?. Based on the suggestion in the first reply there: `my $string_to_check = "yyy foo-bar doo zzz"; my $set = '[\w-]'; my $b = qr/(?<=$set)(?!$set)\|(?<!$set)(?=$set)/; for my $check ("foo-bar doo", "bar doo") { if ($string_to_check =~ /$b$check$b/) { print "$check matched\n"; } }` [download]	[reply] [d/l]
Re: Word boundary in regexp by JavaFan (Canon) on Jan 25, 2012 at 21:16 UTC
Another way, using "modern" regexp verbs: `/$check(?:\S(COMMIT)(FAIL))?+\|\S+(SKIP)(FAIL)/` [download]	[reply] [d/l]
Re: Word boundary in regexp by JavaFan (Canon) on Jan 25, 2012 at 21:04 UTC
Untested: `/(?<!\S)$check(?!\S)/` [download]	[reply] [d/l]
Re: Word boundary in regexp by Anonymous Monk on Jan 25, 2012 at 22:27 UTC
Wow, thanks! Everything works fine! Lynn	[reply]