Anytime you need to look ahead, just loop by indexes instead of by element. 
while (my $in = <IN>) {
  for my $i (0..$#ref) {
     if ($ref[$i] =~ m/$in/) {
        print OUT $ref[$i+1];
     }
  }
}

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In reply to Re: Getting values for next array iteration when matching current by wind
in thread Getting values for next array iteration when matching current by naturalsciences

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