Fixed by deleting leading white space, in my code: 
use strict;
use warnings;

my $row ="";
my $inarray=0;
while (<DATA>) {
    chomp;
    s/^\s+//;  # <-- New line added <----
    if (/^array|^unassigned/){
        print "$row\n" if $inarray;
        $row=$_;
        $inarray=m/^array/;
        next;
    }
    next unless $inarray;
    $row .= " $_";
}
print "$row\n" if $inarray;
__DATA__

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        "You're only given one little spark of madness. You mustn't lose it."         - Robin Williams

In reply to Re^9: Join multiple lines in a string based on regex. by NetWallah
in thread Join multiple lines in a string based on regex. by pr33

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