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Extract Sub String

by gvinu4u (Acolyte)
on Jun 21, 2011 at 06:04 UTC ( #910687=perlquestion: print w/ replies, xml ) Need Help??
gvinu4u has asked for the wisdom of the Perl Monks concerning the following question:

# I want to extract the string from start till "_RVCT22" in the mentioned string, please help me with the same. The below program does not give me any output
$string = "Viood_ram_shiva_RVCT22"; if ($string =~/(.*?)\"_RVCT"/) { print "The file name is $1. "; }

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Re: Extract Sub String
by Ratazong (Prior) on Jun 21, 2011 at 06:08 UTC
    if ($string =~/(.*?)\"_RVCT"/)
    Why do you have the \" in your regex? Remove it! And while you are at it, also remove the other " in your regex (that is not part of your $string itself, but the delimiter for perl)
      Thanks a lot I did exactly what you told
Re: Extract Sub String
by alfie (Pilgrim) on Jun 21, 2011 at 07:12 UTC
    Actually you might want to take a look at Death to Dot Star! why you shouldn't use .* in regexps, not even with ?. Also, there is no " in your screen, so there is no need to match it. Also, " is not a special character inside a regex. As a general advice, you might want to read up the perlre manual again.

    --
    use signature;
    signature(" So long\nRhonda");
Re: Extract Sub String
by sanku (Beadle) on Jun 21, 2011 at 11:52 UTC
    Hi, Try this one...
    $string = "Viood_ram_shiva_RVCT22"; if ($string =~/(\w+)(_RVCT)/) { print "The file name is $1. "; }
      if ($string =~/(\w+)(_RVCT)/)
      There is no need for the capturing parentheses around _RVCT:
      use warnings; use strict; my $string = "Viood_ram_shiva_RVCT22"; if ($string =~ /(\w+)_RVCT/) { print "The file name is $1. "; }
Re: Extract Sub String
by toolic (Chancellor) on Jun 21, 2011 at 15:00 UTC
    Tip #9 from the Basic debugging checklist is to use YAPE::Regex::Explain to demystify Perl regular expressions:
    The regular expression: (?-imsx:(.*?)"_RVCT") matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?-imsx: group, but do not capture (case-sensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- ( group and capture to \1: ---------------------------------------------------------------------- .*? any character except \n (0 or more times (matching the least amount possible)) ---------------------------------------------------------------------- ) end of \1 ---------------------------------------------------------------------- "_RVCT" '"_RVCT"' ---------------------------------------------------------------------- ) end of grouping ----------------------------------------------------------------------
      Thanks to all finally I got this working
      my ( $filename ) = $line =~ /(.*?)_RVCT/;

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