note AnomalousMonk <blockquote><i> ... move it pairwise along the string (bubble it). </I></BLOCKQUOTE> <p> As I understand it, this won't work because substitution is not being done on the original string during the actual substitution process; rather, an intermediate string is being built up during this process, and the intermediate string is copied to the original string when the process is complete. </P> <p> That's why something like <br> <c> ($x = $y) =~ s{foo}{bar}xms;</c> <br> works as it does: instead of copying the intermediate back to the original string ($y), it's copied to another string ($x) leaving the original string untouched. (Or maybe $x is just used as the 'intermediate' in the first place. Whatever...) </P> 1004804 1004804