perlassassin27 has asked for the wisdom of the Perl Monks concerning the following question:

Hi monks i have a little question which hopefully u cud help with. i am trying to compare versions of some software and they are in a string of X.Y.Z format. so to compare these versions i thought of using substring but the problem that arises is that the format can be in a X.YY.Z or X.Y.ZZ format as well i was hoping to use regular expressions for this but i could only find expressions to match strings and not to grab certain parts of the string. 
#!/usr/bin/perl

# Checking of ETS version
my $version;
open (VERSION,'path');
while (<VERSION>){
$version=$_;
chomp ($version);
}
my ($X,$Y,$Z);
if ($version =~ /(\d\.\d\.\d)/)
{
$X = substr $version, 0, 1,;
$Y = substr $version, 3, 4,;
$Z = substr $version, 6, 7,;
}
elsif($version =~ /(\d\.\d\d\.\d)/)
{
$X = substr $version, 0, 1,;
$Y = substr $version, 3, 5,;
$Z = substr $version, 7, 8,;
}

elsif($version =~ /(\d\.\d\.\d\d)/)
{
$X = substr $version, 0, 1,;
$Y = substr $version, 3, 4,;
$Z = substr $version, 7, 9,;
}

elsif($version =~ /(\d\.\d\d\.\d\d)/)
{
$X = substr $version, 0, 1,;
$Y = substr $version, 3, 5,;
$Z = substr $version, 7, 9,;
}


print "X,Y,Z Values are $X,$Y,$Z";

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pls note that as of nw i am only trying to get the values from the string and nothing else. and as u can see it is nt a very efficient way of doing it. i was hoping u monks would have a better idea of doing it efficiently

Replies are listed 'Best First'.
Re: regular Expression
by toolic (Bishop) on Mar 15, 2011 at 18:30 UTC
    See perlre (Capture buffers). 
    use warnings;
use strict;

while (<DATA>) {
    if (/ ^ (\d+) [.] (\d+) [.] (\d+) $ /x) {
        print "$1 $2 $3\n";
    }
}

__DATA__
7.55.3
12.0.2

    [download]
    Prints: 
    7 55 3
12 0 2

    [download]

    Update: I noticed your update, and maybe you want to restrict it to 1- or 2-digit only: 

        if (/ ^ (\d{1,2}) [.] (\d{1,2}) [.] (\d{1,2}) $ /x) {

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Re: regular Expression
by ikegami (Patriarch) on Mar 15, 2011 at 18:45 UTC
[reply]
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Re: regular Expression
by umasuresh (Hermit) on Mar 15, 2011 at 18:27 UTC
    Would this help 
    my ($x,$y,$z) = $version =~/(\w+)\.(\w+)\.(\w+)/;

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    Note: untested, need an example of $version!
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Re: regular Expression
by repellent (Priest) on Mar 16, 2011 at 04:34 UTC 
    my $is_later =
  ( version->parse("1.23.4") > version->parse("5.6.78") );

    [download]

    Example:
    use warnings;
use strict;

for my $vs (
    [ qw( 1.1.1    1.01.1 ) ],
    [ qw( 1.23.4   1.22.4 ) ],
    [ qw( 1.23.4   2.02.1 ) ],
    [ qw( 1.3.42   1.02.1 ) ],
    [ qw( 8.27.32  8.27.17 ) ],
) {
    my ($v1, $v2) =
      map { version->parse($_) }
      @{ $vs };

    my $c =
      $v1 == $v2
        ? "=="
        : $v1 > $v2
          ? ">"
          : "<";

    print "$v1 $c $v2\n";
}

__END__

1.1.1 == 1.01.1
1.23.4 > 1.22.4
1.23.4 < 2.02.1
1.3.42 > 1.02.1
8.27.32 > 8.27.17

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