In the absence of being able to come up with a single line of code for regular expressions I've combined the split suggestions with a regular expression to achieve the desired result. Here is the working code: 

my @section;
my $i = -1;
foreach (split /\n/, $str) {
    if (/^===Comments===$/) {
        ++$i;
        next;
    }
    next unless $i >= 0;
    $section[$i] .= "$_\n";
}
my $comments1;
my $comments2;
my $comments3;

if ($section[0] =~ /\n(.*?)=Microarray Data=/gs){
$comments1 = $1;
}
if ($section[1] =~ /\n(.*?)=Pathway Information=/gs){
$comments2 = $1;
}
if ($section[2] =~ /\n(.*?)=Aditional Info=/gs){
$comments3 = $1;
}

print $comments1, $comments2, $comments3;

[download]

Thanks for all pointers. If anyone can think of a way of making this neater and simpler that would be great. But otherwise it's working so I'm happy!

Thanks.

In reply to Re: Regular Expressions Challenge by danj35
in thread Regular Expressions Challenge by danj35

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