If you want to match across multiple lines, you need to keep multiple lines in memory, but the problem is your while (<INFILE>) only reads one line at a time. So for Athanasius's solution to work, you need to read the entire file into memory ("slurp"), which you can do like this:

open my $ifh, '<', $infile or die "$infile: $!";
my $data = do { local $/; <$ifh> };
close $ifh;

[download]

Note that you really should Use strict and warnings, and some other more modern features like lexical filehandles and the three-argument open like I am showing here.

Another approach is to read the file line-by-line, and keep some state in memory. Since you are reading from multiple input files, I suspect you might want to treat them as a continuous stream of input? If so, then for the above approach, you'd have to slurp all the files into memory and concatenate them, which might be a lot, depending on the size of the input files. But that's not necessary for the line-by-line approach:

use warnings;
use strict;
use File::Glob ':bsd_glob';

my @infiles = sort glob 'SBNUM_*.txt';
my $outfile = 'v2test.txt';

open my $ofh, '>', $outfile or die "$outfile: $!";
my ($prevleft,$prevright);
for my $infile (@infiles) {
    open my $ifh, '<', $infile or die "$infile: $!";
    while (<$ifh>) {
        my ($left,$right) = /^(\d{3}),-->(\d{3}),$/
            or die "Couldn't match '$_'";
        if (defined $prevleft) {
            print $ofh "$prevleft,-->$right,\n";
        }
        ($prevleft,$prevright) = ($left,$right);
    }
    close $ifh;
}
close $ofh;

[download]

Or, just for fun, the same code as a oneliner:

perl -nle '/^(\d{3}),-->(\d{3}),$/||die;defined$x&&print"$x,-->$2,";$x
+=$1' SBNUM_*.txt >v2test.txt

[download]

In reply to Re: Multi Line Regex Matches... by haukex
in thread Multi Line Regex Matches... by tj999

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