make all
./ejb level
where:
level a value from -128 to 127
./try.sh
A negative argument plays the patience puzzle. An argument greater than 0 plays the Tower of Hanoi puzzle. In either case the absolute value of the argument specifies the size of the respective puzzle. Refer to the web pages hanoi.html and patience.html for more information on these puzzles.
Of course, you need a different kind of “patience” if you give the argument 127 to this program and want to see it finish!
We note that this also works under macOS just fine.
./ejb 5
The format of the output for the Towers of Hanoi case is simply a text description of how to solve the puzzle.
./ejb -6
For the patience puzzle, the output is a sequence binary codes representing
successive states of the puzzle. The rightmost digit represents the first ring.
A 1
means the ring is on the U
; a 0
means it is off the U
. The program
prints the word "Invalid"
in response to illegal command line parameters.
Most people who have written software for other people have been
asked to count lines of code. Naturally, this brings up the
controversial question of exactly what defines a line of code.
This program serves to show that counting semicolons will not
always provide a meaningful measure of code size. This is
especially true in this program where the number of semicolons
itself is ambiguous. Does it have two or three? In addition, the
only C keyword this program uses besides type names and
qualifiers is return
, and the only function defined in the code
is main()
. The level of complexity of the program without multiple
semicolons, statements, and functions is achieved by abusing C
operators, especially the comma operator. Considerable use of ||
,
&&
, and ?:
helps too. In addition, main()
is called recursively.
The NULL pointer that terminates argv
is used to pass additional
information into main()
. Even though the algorithms used by this
code are simple, this program is still hard to follow even when
indented properly. (It is pretty hard to indent this code
reasonably, however.)
Although this program has only been tested on UNIX systems it will probably run
on just about any machine with an ANSI C compiler. It does not use the C
preprocessor at all. The only functions it uses are atoi()
, malloc()
,
memset()
, printf()
, and puts()
. It does, however, require that the
architecture it runs on have bytes that are at least eight bits long and
pointers that are at least four bytes long. In addition, it requires an ANSI
compiler since it uses signed char
and ANSI-style function declarations.