ioccc/1994/schnitzi

Best Layout:

Mark Schnitzius
ISX Corporation
1165 Northchase Pkwy, Suite 120
Marietta, GA 30067
USA

To build:

    make all

To run

./schnitzi < textfile

Judges' comments

Try:

./schnitzi < /etc/motd
./schnitzi < schnitzi.c

Compare the output of the program with its source.  Sure the output
is different, but there is more than meets the diff's eye.  Can you
find out why?

Author's comments

SPOILER:

This is a program which takes any text file as input and 'flips'
the input file along a diagonal running from the top left corner
down to the bottom right.  In other words, the first row in the
file ends up written down the first column of the result, the
second row is written down the second column, etc. The program
is run by redirecting a file into the executable on the command
line; for instance, for the included 'info' file, the program
would be run as follows:

	schnitzi < info

The program generates interesting results when its source file is
used as input:

	schnitzi < schnitzi.c

The result of this command is a program which does the exact same
thing -- in other words, both the program and the "flipped"
version of itself work identically (you'll need to redirect the
output of the above command into a separate file and compile it).
You might notice some differences in the flipped version, though.
First off, a secret message becomes visible that was not visible
in the original program.  Also, much of the code shows up in 
different places in the flipped program than it appeared in the
first program.  My first version of this program was perfectly 
symmetrical along the diagonal, but later found out there were
interesting ways to break the symmetry.  The best way to see this 
is to load both the original and flipped versions of the program
into an editor and switch back and forth between them rapidly.

C tokens longer than a character (such as "main") proved difficult
to use in both the original and flipped versions (after flipping,
they show up as a string of single letters on successive lines).
However, I found that it was possible to get around this through
a few well-placed comments.  An earlier version of this program
used nearly every single-character token in the "shared" area;
however, it proved to be too large for contest guidelines (although
the code itself is only about 300 characters, the extra whitespace
needed to pad it put it over the limit -- it nearly filled a 79 by
79 area, adding up to over 4000 total characters).  I will provide
this other version to anyone interested -- contact me by email
at schnitzi@east.isx.com.

Copyright (c) 1994, Landon Curt Noll & Larry Bassel. All Rights Reserved. Permission for personal, educational or non-profit use is granted provided this this copyright and notice are included in its entirety and remains unaltered. All other uses must receive prior permission in writing from both Landon Curt Noll and Larry Bassel.