Text match

NorthShore44 has asked for the wisdom of the Perl Monks concerning the following question:

Monks- I'm running a program that searches for a text match within a txt file and I'm currently able to pull the text after the match, but how can I adjust my code to also pull text before the match? I'm currently able to pull the twenty lines of text after the match, but how can I pull, say twenty lines of text before the match as well? Thanks!

Comment on Text match

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Re: Text match by kennethk (Abbot) on Oct 14, 2009 at 14:40 UTC
It's certainly be helpful if you posted some code - see How do I post a question effectively?. Do you have all your lines in an array? Do you have the whole file in a string? The solution depends strongly on these questions. Assuming you want to do it streaming, perhaps you mean something like: `while (defined (my $line = <$file>)) { push @cache, $line; shift @cache if @cache > 20; print join "\n", @cache if $line =~ /test/; }` [download]	[reply] [d/l]
Re: Text match by rovf (Priest) on Oct 14, 2009 at 14:34 UTC
You could, for instance, always keep the most recent 20 lines of text. -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l]
Re: Text match by lima1 (Curate) on Oct 14, 2009 at 15:18 UTC
See for example How do I retrieve the position of the first occurrence of a match? to get the position of the match. Then you could just use substr. Update: didn't read your question carefully, thought you were talking about characters, not lines.	[reply]