perlquestion Anonymous Monk <p>Dear Monks,</p> <p>I have a problem I am trying to solve with regular expressions. I want to return all locations of an array of patterns inside a string. I also only want the patterns to match at locations which are a multiple of 3. For example, so far I have the following.</p> <code>my $string="AAABBBCCCCDDDEEEFFFGGGHHHIII"; my @patterns=('BBB','DDD'); my @index; foreach(@patterns){ while($string=~m/([A-Z]{3})+?$_/g){ push(@index,$-[2]); pos($string)=$-[2]; } </code> <p>The problem with this is that it matches the first pattern correctly, but it will also match 'CCCDDD' in the second loop because I cannot/dont know how to anchor the pattern to start at a specific location.</p> <p>To be clear, I only want the patterns in the array to match if there are a number of characters evenly divisible by three before it.</p> <p>Is there a good way to do this?</p> Thanks 6