Re: Re: boundary reg expression

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Re: Re: Re: boundary reg expression by allolex (Curate) on Jul 21, 2003 at 15:01 UTC
Well, sort of ;) Take these examples: `s/\bold\b/new/gi; # 1: replaces all instances of the string, e.g. "old", # "OLD", "Old", "OlD" on either side with "new". s/\bold\b/new/g; # 2: replaces "old" with "new" -- case sensitive here. s/\bOLD\b/NEW/g; # 3: replaces "OLD" with "NEW" s/\bOLD\b/NEW/gi; # 4: replaces same variants of "OLD" as in 1 with "NEW"` [download] So, to finally answer your question: yes, but I think you might need that other "\b". Something that might help you a lot, as it did for me, is YAPE::Regex and YAPE::Regex::Explain by our very own japhy. They can be downloaded off the CPAN. For example: `#!/usr/bin/perl use YAPE::Regex::Explain; print YAPE::Regex::Explain->new(qr/\bold\b/i)->explain;` [download] gives the following explanation. The regular expression: (?i-msx:\bold\b) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?i-msx: group, but do not capture (case-insensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- \b the boundary between a word char (\w) and something that is not a word char ---------------------------------------------------------------------- old 'old' ---------------------------------------------------------------------- \b the boundary between a word char (\w) and something that is not a word char ---------------------------------------------------------------------- ) end of grouping ---------------------------------------------------------------------- [download] -- Allolex	[reply] [d/l] [select]
(jeffa) 3Re: boundary reg expression by jeffa (Bishop) on Jul 21, 2003 at 15:06 UTC
Add a boundary to the beginning and that should do the trick (watch out for words like FOLD, TOLD, etc). Also note that you don't need to write a full Perl script to make the changes to the files in question. You can do this with a one-liner: `perl -pi -e's/\bOLD\b/NEW/g' .txt` [download] And if you are paranoid and want to keep the orignals: `perl -pi.bak -e's/\bOLD\b/NEW/g' .txt` [download] will preserve them with a `.bak` "extension" added to the end of the filename. (For example, `foo.txt` becomes `foo.txt.bak`) jeffa L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)	[reply] [d/l] [select]