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Path: utzoo!linus!philabs!cmcl2!floyd!harpo!eagle!mhuxl!ihnp4!ihu1g!fish
From: fish@ihu1g.UUCP (Bob Fishell)
Newsgroups: net.jokes.d
Subject: Home-grown de-rotator
Message-ID: <115@ihu1g.UUCP>
Date: Fri, 30-Dec-83 15:23:36 EST
Article-I.D.: ihu1g.115
Posted: Fri Dec 30 15:23:36 1983
Date-Received: Sat, 31-Dec-83 11:44:26 EST
Organization: AT&T Bell Labs, Naperville, IL
Lines: 37

If any of you are disappointed with Caesar, or if you need something
to decode saved jokes, I have a little program that works half-way
decent and runs very fast.  Here it is:

#include <stdio.h>
#include <ctype.h>
#define begin {
#define end; }

main ()

/* does a 13-character rotation on alpha strings and
   copies the result to std out. */
begin
short c;
while ((c = getchar())!= EOF)
        begin
  
         if (isupper(c))           /* A-Z? */
         begin
              c = ( (c - 'A' + 13) % 26) + 'A';
         end;
   
         if (islower(c))           /* a-z? */
         begin
              c = ( (c - 'a' + 13) % 26) + 'a';
         end;

         putchar(c);

        end;
end;

The program can be used for both rotation and derotation.  
Bugs: rotates unrotated portions of the file.
      "C" purists will flame about the begin/end; substitutions for
      those thq qnza(rot13), illegible little braces...