Further to GotToBTru's comments on the obscurity of the string transformations you're trying to achieve, one more thing puzzles me. There are several statements of the form
    print "$part_of_final_string" or next;
that will output an incompletely transformed string and then go on to process the next input string if the print I/O operation fails. In this unlikely (and probably catastrophic) event, don't you really want to die with an appropriate error message rather than trying to press on? Just curious...