Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!lll-winken!taco!taco.cc!setzer
From: setzer@matagh.ncsu.edu (Th'PoC)
Newsgroups: comp.lang.perl
Subject: Manipulating strings
Message-ID: <SETZER.91May23110013@matagh.ncsu.edu>
Date: 23 May 91 18:00:13 GMT
Sender: news@ncsu.edu (USENET News System)
Organization: The Chebychev Church of Probability
Lines: 29
X-Communicated:  That royal king-type dude that had Becket snuffed

The problem: I have four files of identical length (< 5k).  Each
contains 8 bit data, but do not contain any of `A'..`Z'.  At any fixed
offset into each file, either 1) all four characters are identical, or
2) one or more of the characters has the eighth bit set.  I want to
generate an "overlay", i.e., if (1), output the character; if (2),
output a letter in `A'..`P' that will tell me which files had the
eighth bit set.

The [*ugly*] solution:  I `open'ed the four files, slurped each
of them into an array, and looped over the length of the array:

--
open(A, "< a") || die "can't open 'a'";  @a=split(//,join("",<A>));
# do the same for files "b", "c", and "d"

for ($i=0; $i < $#a+1; $i++) { # do the `if's on `ord($a[$i])&0x80' etc.
--

The question: Is there a "prettier" way to do this?  (There must be.
Isn't there a perl axiom that if you have to use an indexing variable,
you're doing it the "wrong" way?)  It comes down to simple string
manipulation, but I can't see a way to use any of the implicit looping
constructs (`for (@a)', `foreach ...').  I would appreciate insight
into an alternate way to solve the problem.  Thanks.

Wm.
--
If the fundamentalists don't hate you, you have the wrong lifestyle.
  -- James Nicoll