Path: utzoo!attcan!uunet!snorkelwacker!ira.uka.de!fuchs
From: fuchs@it.uka.de (Harald Fuchs)
Newsgroups: comp.lang.perl
Subject: unctrl
Message-ID: <fuchs.656085531@tmipe1>
Date: 16 Oct 90 13:58:51 GMT
Sender: news@ira.uka.de (USENET News System)
Organization: University of Karlsruhe, FRG
Lines: 28

I'm looking for the most elegant (terse?) way to do an 'unctrl'
operation on a string, i. e. to replace all occurrences of
non-printable characters by a printable representation.
Examples: \001 -> ^A
          \177 -> ^?
          \232 -> M-^Z

The only way I could find was:

while (<>) {
  while (/[\200-\377]/) {
    $c1 = $&;
    $c2 = pack ('C', ord ($c1) - 0200);
    s/$c1/M-$c2/;
  }
  while (/[\000-\011\013-\037]/) {
    $c1 = $&;
    $c2 = pack ('C', ord ($c1) + 0100);
    s/$c1/^$c2/;
  }
  s/\177/^?/g;
  print;
}

How about a one-liner, Randal?
--

Harald Fuchs <fuchs@it.uka.de> <fuchs%it.uka.de@relay.cs.net> ...