use strict;
my $str = 'ABC_0000_0.0.0.xyz
Group 1 : ABC
Group 2 : 0000
Group 3 : 0.0.0
Group 4 : <empty>
Group 5 : <empty>
ABC_0001_0.1.0_N.xyz
Group 1 : ABC
Group 2 : 0001
Group 3 : 0.1.0
Group 4 : _N
Group 5 : <empty>
ABC_0002_1.1.2_foo.xyz
Group 1 : ABC
Group 2 : 0002
Group 3 : 1.1.2
Group 4 : <empty>
Group 5 : _foo
ABC_0002_42.42.42_N_bar.xyz
Group 1 : ABC
Group 2 : 0002
Group 3 : 42.42.42
Group 4 : _N
Group 5 : _bar';
my $regex = qr/^(ABC)_([0-9]{4})_([0-9]+\.[0-9]+\.[0-9]+)(_[a-zA-Z])?(_[a-zA-Z]+)?\.xyz$/mp;
if ( $str =~ /$regex/g ) {
print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n";
# print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n";
# print "Capture Group 2 is $2 ... and so on\n";
}
# ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p'
# Named capture groups can be called via $+{name}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html