Files
ioccc/2000/anderson/index.html
T
Landon Curt Noll 4ee4c731f7 convert markdown copyright TAB chars into SPACE chars
While not strictly necessary, replacing the two ASCII tab characters
in the markdown copyright comment makes it easier to detect problematic
TAB indentation within markdown files.

After this commit, only 90 markdown files have leading ASCII TAB
characters.  And again, while not strictly necessary, we can consider
running expand on those 90 markdown files to see what effect that
might have on the HTML files they produce.

Replace leading ASCII TAB characters with multiples of 8 ASCII SPACE
characters (the default action of the `expand(1)` tool) might have
an negative effect on some HTML formatting where **hack-a-round**
formatting was attempted to fix broken indentation caused by
problematic ASCII TAB characters.

Think of this as a baseline for evaluating leading
TAB characters within markdown files.

TODO: Consider either using `expand(1)` to replace leading ASCII
TAB characters with multiples of 8 ASCII SPACE characters AND/OR
modifying the appropriate `bin` tool to convert leading ASCII TAB
characters into multiples of 8 ASCII SPACE characters.
2024-06-22 22:15:25 -07:00

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<h1>The International Obfuscated C Code Contest</h1>
<h2>2000/anderson - Best use of flags</h2>
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<div class="navbar">
<a class="Left Disabled" href="#">first entry</a>
<a class="Left" href="../index.html">&uarr; 2000 &uarr;</a>
<a class="Left" href="../bellard/index.html">bellard &rarr;</a>
<a class="Right" href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/anderson.c">C code</a>
<a class="Right" href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/Makefile">Makefile</a>
<a class="Right" href="#inventory">Inventory</a>
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<h2 id="author">Author:</h2>
<ul>
<li>Name: <a href="../../authors.html#Glyn_Anderson">Glyn Anderson</a><br>
Location: <a href="../../location.html#ID">ID</a> - <em>Republic of Indonesia</em> (<em>Indonesia</em>)</li>
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<h2 id="to-build">To build:</h2>
<pre><code> make</code></pre>
<h2 id="to-use">To use:</h2>
<pre><code> echo something | ./anderson</code></pre>
<h2 id="try">Try:</h2>
<pre><code> ./try.sh</code></pre>
<h2 id="judges-remarks">Judges’ remarks:</h2>
<p>This small program might be a nice addition to a digital personal
organizer; just in case you are stranded on a desert island and need to
signal your distress to passing ships.</p>
<p>The obfuscation in this program is truly masterful. The program is
very cleverly obscured without the use of a single <code>#define</code>!
Reformatting this program by hand :-) is the easiest way to understand
what is going on.</p>
<h3 id="note-about-defines-not-being-used">Note about <code>#define</code>s not being used:</h3>
<p>In 2023 due to annoying warnings triggered at different times, sometimes
interspersed with the output of the program (this happens in macOS), many
entries were changed to use <code>fgets(3)</code> instead. However to make the entries more
like the original we redefined <code>gets</code> to use <code>fgets</code>. Unfortunately it’s not
possible to do it through <code>-Dfoo</code> compiler options so there is a <code>#define</code> in
the code now.</p>
<h2 id="authors-remarks">Author’s remarks:</h2>
<p>This program is a simple filter that translates ASCII text into
semaphore code. It reads from standard input and converts all
alphanumeric characters to their corresponding semaphore codes.
Consecutive whitespace is translated as a single ‘break’ code. Newlines
also cause the next code to be output on a new line. All other
characters are ignored. The codes themselves are written to standard
output as a depiction of a person holding two flags, using only ASCII
characters (semaphore smileys, if you will). For example, given the
input “Hello, world!”, the output will be:</p>
<pre><code> &lt;&gt; &lt;&gt; &lt;&gt; &lt;&gt; &lt;&gt; &lt;&gt;
_() ()/ ()/ ()/ _\) () (/_ _\)
[] /^ |^^ /^^ /^^ [] ^^ |^^| ^^ [] [] ^^
&lt;&gt;[ [][ &lt;&gt;][ &lt;&gt;][ ][ [][] ][ ][
&lt;&gt; []
_()_ ()/ |() ()
[] ^^ [] /^^ ^^| |^^|
][ &lt;&gt;][ ][] [][]</code></pre>
<p>The program is obfuscated without the use of the preprocessor or any
special compilation parameters. In fact, the program doesn’t even
bother using any keywords, save the single <code>char</code> at the beginning.
This program was crafted using only operator precedence rules,
short-circuit evaluation and recursion. Each function contains a
single, non-empty statement. (I did have to add a couple of empty
statements to format the code properly.) There is a single string
constant which encodes the flag positions and other data needed for
drawing the semaphore codes.</p>
<p>The preprocessor will provide no help in de-obfuscating this code, and a
C beautifier won’t get you very far either. You just have to crunch
through it.</p>
<p>An ANSI C compiler will generate several warnings when it compiles this
program, as none of the functions declare their return type, nor do they
return anything. This was necessary to keep the program free of
keywords. It’s valid in K&amp;R C, and compiles in ANSI C. There are also
warnings about conversion from <code>int</code> to <code>char</code> and the resulting loss of
data. Again, if it’s OK with K&amp;R, it’s OK with me.</p>
<p>This program is a great teaching tool for learning the semaphore code;
and if you don’t have any flags handy you can just use two copies of the
source file.</p>
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<div id="inventory">
<h1 id="inventory-for-2000anderson">Inventory for 2000/anderson</h1>
</div>
<h2 id="primary-files">Primary files</h2>
<ul>
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/anderson.c">anderson.c</a> - entry source code</li>
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/Makefile">Makefile</a> - entry Makefile</li>
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/anderson.orig.c">anderson.orig.c</a> - original source code</li>
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/try.sh">try.sh</a> - script to try entry</li>
</ul>
<h2 id="secondary-files">Secondary files</h2>
<ul>
<li><a href="2000_anderson.tar.bz2">2000_anderson.tar.bz2</a> - download entry tarball</li>
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/README.md">README.md</a> - markdown source for this web page</li>
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/.entry.json">.entry.json</a> - entry summary and manifest in JSON</li>
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/.gitignore">.gitignore</a> - list of files that should not be committed under git</li>
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/anderson/.path">.path</a> - directory path from top level directory</li>
<li><a href="index.html">index.html</a> - this web page</li>
</ul>
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<div id="coda"><h3>Coda</h3>
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