CS 1MD3 T2 2003
Bonus Assignment #1

• Due: Monday January 20, before class, by email
• Write a readable C program that
  • Takes an integer N on the command line
  • Outputs a file rotN.c where the N should be the input integer
  • The program contained in rotN.c should:
    • Take as input any ASCII file on stdin
    • Rotate any alphabetic character by N positions (see definition of 'rotate' below, and leave every other character intact.
    • Output the results on stdout
• Further details:
  • The integer N should be a signed 32 bit integer
  • The C file, not counting comments, should be at most 50 lines long
  • The output C file should also be at most 50 lines long
  • The C file(s) will be formatted using standard formatting rules (by the instructor if need be) before counting lines
  • Using 1 (very) long line for a string containing the (inner) C program is not acceptable - that makes the program unreadable.
  • To rotate (a very weak means of encryption) means to replace every character by the one N positions to the right. In other words, to rotate by 1 position means 'a' goes to 'b', 'b' goes to 'c', ..., 'w' to 'z' and finally 'z' to 'a'. Same for upper-case letters.
  • Rotating by a negative number means to go left instead of right.
  • Rotating by 0 (or a multiple of 26) should be equivalent to a no-op
• Deliverables:
  • The C program, as ASCII
• This assignment is worth up to5 bonus points.
• Writing this assignment, under the same conditions, in the languages Ocaml or Haskell is worth up to10 bonus points.
• Writing this assignment, under the same conditions, except for a line limit of 70, in the languages Ocaml or Haskell, and the output program also one of the above, is worth up to12 bonus points.

If your program is called bonus1 then to run it (where > is 
the command line prompt)
> bonus1 5
would produce a file called rot5.c.  When compiled like
> gcc -o rot5 rot5.c
this produces a program executable rot5 (or rot5.exe on Windows).
Assuming one has an ascii file foo, one could run
> rot5 < foo > foo.out
to get a rotated output.  A good test:
> bonus1 -5
> gcc -o rot-5 rot-5.c
> rot5 < bonus1.html | rot-5 > bb.html
> diff bonus1.html bb.html
should produce no output (ie that last 'diff' command should
produce no output), where bonus1.html is the name of this HTML file
you are currently reading.