Cody Boone Ferguson
41abeda97a
In the line in README.md and index.html files that said:
### NOTICE to those who wish for a greater challenge
I added a ':' at the end of the line.
There were some entries that had a link fix in the index.html file but I
only looked up through 1995/leo as those still have to have a 'look and
feel' check and it would just slow things down.
184 lines
7.0 KiB
Markdown
184 lines
7.0 KiB
Markdown
## To build:
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``` <!---sh-->
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make all
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```
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## To use:
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``` <!---sh-->
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./df
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```
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## Try:
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``` <!---sh-->
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./try.sh
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```
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This will run the program in a loop until you exit (`q` when prompted or
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ctrl-c/intr).
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Can you figure out a very simple pipeline to cheat?
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## Judges' remarks;
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Everyone talks about how data hiding can produce clearer code; I am
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pleased to offer this charming refutation.
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The program is a simple game. A bit of observation reveals that the
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game has some data - but where? It's unclear which of the contents of
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the program are used.
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Curiously, the program only works if its source is in the directory
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it's run in. More curiously, the program would fail if the program's
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name's second letter wasn't `r` (the source has been changed for your
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convenience and this restriction no longer exist).
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Modern design has come a long way since the unreadable, tightly-coupled
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systems we used to have.
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Extra credit questions:
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- Where are the words stored?
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- How many words does this entry use?
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- Can you add more words to the program and still make it work?
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- Are there any misspelt words? If yes what are they?
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## Author's remarks:
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This program lets you guess English words. It displays an underscore
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for each letter in the word; guessing a letter that actually is in
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the word replaces the corresponding underscores with the letter
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itself. You can guess a letter simply by typing it in. If your C
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implementation requires it, you may have to hit Return before it
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is recognized. In this case, you can also type multiple guesses
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on the same line (completely solve it by entering
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`abcdefghijklmnopqrstuvwxyz`). Execution stops when all underscores
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have been replaced.
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The program offers a number of different words to guess, `time()` is
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used to pick one at random. All words are eight characters long.
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The source should compile with any ANSI C compiler (I used CodeWarrior
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w/ ANSI strict). Using non-ANSI compilers that implement the ANSI
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features it uses will not work (unless they defined `__STDC__ 1`
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which they shouldn't). Due to space restrictions, I did not use
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any trigraph sequences. It does not require any special `-D` defines.
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The source passes lint without any complaint (if invoked with
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`>/dev/null`). (My lclint is unable to recover from some parts of it.)
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Actually, the code not only is compliant with the ANSI specifications, but uses
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a near minimum subset of them. C keywords that were not used have been
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re(de)fined to avoid unnecessary introduction of new, unknown character
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patterns. The source also includes all ANSI headers it needs (after most of the
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functions have been used), and the declaration of `main()` follows the
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guidelines (but the return type has a different meaning and the arguments are
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either misused or unused). There also may be some compiler warnings. These are
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not bugs, but features. The more warnings, the better the compiler. There
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wouldn't be any if I had been allowed to use some extra space for prototypes
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etc.
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Multiple defines are used (but not all of them define), and `#define
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y define` is used with `#y` but the code doesn't assume `#y` to expand
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to `#define`. I have also included comments in the code, and vital
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code in the comments. And of course there is code that doesn't do
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anything but will crash the program if it is removed (just like
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those comments I mentioned above). Additionally, since you said
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you'd be preprocessing entries ignoring `#include`s I figured I should
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use some more of them instead of other obfuscation methods. Did
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I mention that preprocessed or beautified sources will crash or
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hang your system? The program will also crash on non-ASCII machines.
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The executable needs its source file present in the current directory
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or, depending on your system, in your path. The name of the source
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file is not hard-coded, `__FILE__` is used instead.
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In the original version which was sent in to the contest, there were
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some restrictions on the file name:
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- The second letter had to be a lowercase `r`.
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- The third letter could never be a `+` or a `b`.
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Valid names would have been `pr4.c`, `pr.c`, `prog.c`, `brownie.c` etc.
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My first private version would only run when compiled on a Friday.
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I decided it would be better this way...
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These restrictions have been removed for your convenience.
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### NOTICE to those who wish for a greater challenge:
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**If you want a greater challenge, don't read any further**:
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just try to understand the program via the source.
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If you get stuck, come back and read below for additional hints and information.
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### How this entry works:
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The following lines describe how this program works; if you don't
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want to know it at this time, please skip them. If this entry would
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by some mistake win the contest, please do not rot13 this - I hate
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rot13 spoilers since it is somewhat complicated on a Mac to
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reverse them. Anyone out there should have enough discipline and
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rot13 shouldn't be required, really. After all, we are not children
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anymore :-)
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<hr style="width:10%;text-align:left;margin-left:0">
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This paragraph is not part of the author's remarks, but is a helpful
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gift from the judges; if you read too fast to stop yourself, this should
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give you enough time to stop, which you really need to do RIGHT NOW if
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you don't want to read the obfuscation information: we mean it.
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<hr style="width:10%;text-align:left;margin-left:0">
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The source file needs to be present because the words are read from
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it. The wordlist is encoded within the source using a 24 entry
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sliding dictionary where lowercase letters are offsets into the
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dictionary, uppercase letters are new letters not yet in the
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dictionary, and all other characters are ignored. The words are
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spread over six lines in the source; decoding starts on a line
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after a tab and a whitespace have been found, and stops on a newline.
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The grin after the "Demonic Smiley" actually is one encoded letter
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while the string is completely ignored; and the `cut` in "cut here"
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is required while `here` is not.
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"For extra credit", explain why the words are sorted alphabetically
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(because I extracted them from a dictionary :-) )
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The file name had to fulfill the restrictions mentioned above
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because `__FILE__+1` was used as a second parameter to `fopen()`. (It
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essentially was `fopen(__FILE__,__FILE__+1)` ). This was an extra joke
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that doesn't exist in the released version.
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You probably discovered that the `while(FILE)` in `main()` is not a while loop
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but the statement that opens the file and initializes the dictionary.
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Similarly, `int` and `signed` have been redefined (to save space, of course).
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The main function (the guessing part) is between the last `#else..#endif`,
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but still is declared before `main()`. The `5[O]()` in `main()` calls
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this function. Similarly, most indexing operations have been
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changed to this form and I tried to write each such operation
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different.
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<!--
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Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
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You are free to share and adapt this file under the terms of this license:
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Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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For more information, see:
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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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