my (@array, $keep);
while (<$handle>) {
    if (!@array) {$keep = /FIRST_PATTERN/;}
    next unless $keep; # Next if we haven't seen the first pattern.
    push @array, $_;
    next unless $keep = !/SECOND_PATTERN/;
                       # Next unless the second pattern is seen.
    process_array \@array; # Process and print
    print @array;
    @array = ();
}
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That works very well, but what if the first pattern I am using is the same as the second pattern. For eample, a leading number? Does that mkae sense?

If the patterns are the same, then you actually have a simpler case (though the more complicated one shouldn't break, and is more generalized):

my @array;
while (<DATA>) { last if /^d/ } #discard until the first match
while (<DATA>) {
   if ( @array and /^d/ ) {
      process_array( @array );
      undef @array;
      next;
   }
   push @array, $_;
}
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Of course, depending on the size of your data set, you could slurp and split:

my $data  = join('',<DATA>);
my @chunk = split(/^\d/m, $data);

foreach (@chunk) { process_array( split(/\n/s, $_) ) }
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But this latter assumes your data starts and ends OK (won't skip headers or the like).

<-radiant.matrix->
A collection of thoughts and links from the minds of geeks
The Code that can be seen is not the true Code
"In any sufficiently large group of people, most are idiots" - Kaa's Law

This sounds like it might at least be related to token parsing, in which case Parse::Token might work well for you. Otherwise, it's essentially a simple switch.

my @array;
my $start_regex = qr/^\d{3}:/; # a line beginning with, e.g. 001:
my $end_regex   = qr/^:::$/;   # a line with only ':::'
while (<DATA>) { # replace with your FH
    if ( @array and $_ =~ $end_regex ) {
        # reached an 'end'.  I assume you don't want to keep the end '
+tag'
        do_something_to(@array);
        undef @array;
    }
    elsif ( @array ) {
        # filling array
        push @array, $_;
    }
    elsif ( $_ =~ $start_regex and !eof DATA) {
        # begin filling up the array!
        push @array, $_;  # I assume you want to keep the start 'tag'
    }
    else {
        # we haven't gotten a 'start',
    }
} #_ while{}

# deal with the possibility that we 'started' but didn't 'end'
if (@array) { warn 'Start with out end at EOF!' }
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