regex needed

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

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Re: regex needed by jwkrahn (Abbot) on Nov 18, 2008 at 13:33 UTC
Perhaps you want: `while (<DATA>) { chomp; if ($var eq 'Sensor30') { print "MATCH => $_\n"; } }` [download]	[reply] [d/l]
Re: regex needed by McDarren (Abbot) on Nov 18, 2008 at 13:37 UTC
"If I'm trying to do an exact match..." Exact match for what? You didn't specify what $var contains. Anyway, does this do what you want? `#!/usr/bin/perl -l use strict; use warnings; my $var = 'Sensor30'; while (<DATA>) { chomp; print if m/^\Q$var\E$/; } __DATA__ >Sensor30 >FooSensor30 > Sensor30 Sensor300 Sensor30 >Sensor3` [download] Cheers, Darren	[reply] [d/l]
Re: regex needed by Bloodnok (Vicar) on Nov 18, 2008 at 14:04 UTC
I'm not sure I understand the question - why would your attempt be only finding the 5th in the list - if you're attempting to preclude the possibility of a leading '>', then surely both the 4th & 5th elements of the list should be 'found' - unless of course the snippet is a little too small... Either way, suitable use of `\s` would suffice, such that the snippet might become... `while (<DATA>) { chomp; next if /^>\s/; print "MATCH => $_\n"; } __DATA__ >Sensor30 >FooSensor30 > Sensor30 Sensor300 Sensor30 >Sensor3` [download] Note that inverting the sense of the makes the test for whitespace redundant since the `next` will be executed whenever the line begins with a '>'. To avoid any line whose first non-whitespace char, change `/^>\s/` to `/^\s>/`. A user level that continues to overstate my experience :-))	[reply] [d/l] [select]
Re: regex needed by Anonymous Monk on Nov 18, 2008 at 13:44 UTC
I forgot to mention that I need to exclude the ">" sign if it exists so in this case I would have two matches: `>Sensor30 Sensor30` [download]	[reply] [d/l]
Re^2: regex needed by Crian (Curate) on Nov 18, 2008 at 13:58 UTC
Perhaps this one is, what you are looking for? `C:\Daten\perl>cat match.pl #!/usr/bin/perl use strict; use warnings; my $var = 'Sensor30'; while (<DATA>) { print if /^>?\Q$var\E$/; } __DATA__ >Sensor30 >FooSensor30 > Sensor30 Sensor300 Sensor30 >Sensor3 C:\Daten\perl>perl match.pl >Sensor30 Sensor30` [download] Without a regular expression: `C:\Daten\perl>cat match.pl #!/usr/bin/perl use strict; use warnings; my $var = 'Sensor30'; while (<DATA>) { chomp; print "$_\n" if $_ eq $var or $_ eq '>' . $var; } __DATA__ >Sensor30 >FooSensor30 > Sensor30 Sensor300 Sensor30 >Sensor3 C:\Daten\perl>perl match.pl >Sensor30 Sensor30` [download]	[reply] [d/l] [select]
Re^3: regex needed by Anonymous Monk on Nov 18, 2008 at 14:11 UTC
Thats what I was missing...Thank you! I modified it a bit to include the space if it exists: `my $var = 'Sensor30'; while (<DATA>) { chomp; if (/^(>\s*)?\Q$var\E$/) { print "MATCH => $_\n"; } } __DATA__ >Sensor30 >FooSensor30 > Sensor30 Sensor300 Sensor30 >Sensor3` [download]	[reply] [d/l]
Re: regex needed by JavaFan (Canon) on Nov 18, 2008 at 19:54 UTC
There are various ways to create a regex for this, but I wouldn't create such a one. I'd do (untested): `while (<DATA>) { chomp; my $copy = $_; s/[< ]+//g; print "MATCH => $copy\n" if $_ eq 'Sensor30'; }` [download] But then, I assume you want to ignore greater than signs and spaces anywhere in the line, so you also want to match `Se>>>nsor 30` and `S e n s o r > 3 0`.	[reply] [d/l] [select]