Hi, Can you tell the results from the following? And what is the reasons for the results? line = "abab" print line.sub!(/a/, 'A') + line.sub!(/b/, 'B'), "\n" line = "abab" print line.sub!(/a/, 'A') + " " + line.sub!(/b/, 'B'), "\n" Be careful of the bang. ;-) matz.