This is FAQ version 28.2.24 2025-11-18.
+This is FAQ version 29.01 2025-11-28.
Makefile.example
does have other rules like everything and alt, and we encourage you to use
the one linked to above.
+See also the +FAQ on “detailed Makefile recommendations” +for more details.
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Extra files are defined as files that are not the free files (the required files
prog.c, Makefile, remarks.md and the optional try.sh, try.alt.sh,
@@ -1479,6 +1483,222 @@ Makefile to your Makefile and add to the remarks.md:
Please ignore this submission.
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+We recommend AND encourage you to use the example Makefile,
+as the starting point for your submission’s required Makefile:
Feel free to modify the Makefile to suit your obfuscation needs.
Please add a space between the = and the value of variables, in the
+Makefile, making sure that the = comes immediately after the name. See the
+example Makefile for examples.
The rest of this section and its subsections will assume that you are using some
+variant of the example Makefile, again renamed as Makefile.
We suggest that you compile your submission with a commonly available
+-std=gnu17 (ISO C 2017 with GNU extensions) C compiler, via clang(1)
+and/or gcc(1).
Unless you clearly state otherwise in your remarks.md file, AND put in
+your submission’s Makefile, we will compile using -std=gnu17 -O3!
It is OK if you need to require your submission to NOT be compiled
+using the default -std=gnu17 -O3 settings. Simply explain why
+your submission should NOT be compiled using -std=gnu17 -O3 in
+your remarks.md file, AND adjust your Makefile accordingly.
One reason that you might have to change the flags, is that the optimiser is
+known to break some programs, but there are certainly other possible valid
+reasons. Again, just update the Makefile and explain it in your remarks.md.
+See the optimiser section for details for changing optimiser
+flags.
For more fun when it comes to optimisers breaking code, see +1986/marshall/compilers.html.
+IMPORTANT NOTE: The use of -std=gnu17 does NOT imply the use of the gcc
+compiler! We often start by compiling using the clang C compiler instead.
PLEASE NOTE: in macOS, the compiler gcc found at /usr/bin/gcc is
+in truth the clang compiler, as /usr/bin/gcc --version will show!
You may change the standard under which your submission is compiled
+by modifying the CSTD Makefile variable. For example, to use c99 instead:
CSTD= -std=c99You may change the level of optimization and compiler debug level
+that your submission is compiled with, by modifying the OPT Makefile variable.
+For example, to compile without optimization, and to include debug symbols:
OPT= -O0 -g3The default warning flags are set via the CWARN variable, as shown in the
+example Makefile:
# Common C compiler warning flags
+ #
+ CWARN= -Wall -Wextra ${CSILENCE} ${CUNKNOWN}For details on CSILENCE and CUNKNOWN, see the section on disabling
+warnings.
-Weverything optionWe do NOT recommend that you put
+the use of -Weverything into your submission’s Makefile for the reasons
+cited there. This goes even if your version does not trigger a warning as some
+other version might!
On the other hand, if ${CC} has “clang” in the name, the example Makefile will
+automatically enable -Weverything, so you might have to use -Wno-foo
+options anyway, as detailed below.
If “clang” is NOT in ${CC}, the CWARN variable will not be further
+modified.
There is no real penalty for compiler warnings. Sometimes +compiler warnings cannot be helped: especially in the case of +obfuscated C. :-) So if you cannot easily get rid of a compiler +warning, try not to fret too much.
+We LIKE code that has a minimum of warnings, especially under the
+more strict -Wall -Wextra -pedantic mode:
CWARN= -Wall -Wextra -pedanticThe two previous guidelines might be thought by some as being somewhat +contradictory. Isn’t life, and isn’t trying to satisfy “contradictory customer +requirements” all too often like that? :-) Try to minimize warnings if you +can.
+If you manage to produce very few warnings, or perhaps no warnings at
+all under the -Wall -Wextra -pedantic mode, then by all means brag about it in
+your remarks.md file AND BE SURE TO TELL US the OS, OS version, compiler
+and compiler version in which you observed this occurring (in case our OS and
+compiler produces a different result: so your submission won’t be penalized for
+not meeting your claims).
On the other hand, some warnings cannot be disabled and are enabled by compilers +without any warning option specified. These are sometimes inevitable in +obfuscated code and even in some non-obfuscated code, and you should not worry +about this, though it might be worth pointing out.
+For instance, some compilers like to warn about use of pointers as arrays, which seems to
+be dubious, as it obviously can’t (always) be avoided, being a big part of C, so
+you should not worry about this either; this is the warning
+-Wunsafe-buffer-usage and the way to disable it is -Wno-unsafe-buffer-usage.
If your submission issues lots of warnings but is otherwise
+marvelously obfuscated in multiple levels, don’t worry about it. Nevertheless,
+be sure that the warnings do not constitute a potential “show stopper”
+compiler problem. Be sure that compilers such as both gcc and clang won’t
+produce a compiler error and refuse to compile your code: unless for some
+reason that is what you intend to happen in which case document that too in your
+remarks.md file. :-)
All other things being equal, a program that must turn off fewer +warnings will be considered better, for certain values of better.
+To turn off a compiler warning, in your submission’s Makefile,
+try something such as:
CSILENCE= -Wno-some-thing -Wno-another-thing CSILENCE= -Wno-parentheses -Wno-binding-in-condition -Wno-misleading-indentationIf you need to define something on the compile line, use
+the CDEFINE Makefile variable. For example:
CDEFINE= -Dfoo -Dbar=bazNOTE: just because we offer a default way to use the -D option, we still
+do not like excess use of -D to get past size limits, especially since you
+could use #define in your code instead.
If you need to include a file (as in #include) on the command line, use the
+CINCLUDE Makefile variable. For example:
CINCLUDE= -include stdio.hIf you need to add other “magic” flags to your compile line,
+use the COTHER Makefile variable. For example:
COTHER= -fno-math-errnoNOTE: We only recommend using “magic” flags if BOTH gcc
+and clang support it.
Again, please note that in macOS, /usr/bin/gcc is actually clang!
When make clobber is invoked, we request that submissions be restored
+to their original submission state. For example, any temporary files
+(including the compiled program(s)) created during the build process, or
+during execution should be removed by the clobber rule. In other words, the
+only things that should be in the directory after running make clobber is what
+is in your submission tarball itself.
While people are free to manage their submission under git(1) or even use a
+GitHub repo, dot-files and dot-directories such as .git are not allowed in a
+submission.
The mkiocccentry(1) tool will ignore dot-files and dot-directories (such as
+.vimrc, .bashrc, .git and .github) and not put them in the submission’s
+compressed tarball. So while you may use such files and
+directories to help develop your submission, they won’t be included when you run
+the mkiocccentry(1) tool.
Even if you did manage to get dot files or dot directories in the tarball
+somehow, txzchk(1) will flag it as an error. When the judges run txzchk(1)
+on the uploaded submission compressed tarball, if anything is wrong, for
+instance if you “sneak in” any dot files or dot directories, the submission
+WILL BE REJECTED for violating
+Rule 17 - Packaging!
You may use whatever tools you need to develop your submission, including the
+use of git(1) or gh(1), just be sure that your submission code and your
+submission Makefile don’t depend on such tools.
Of course if you do use GitHub to work on your submission, you might want to +make the repo private so you don’t reveal who you are. :-)
+ + +In other words, for make clobber, do something like:
clobber:
+ ${RM} -f foo bar bazand NOT something like this:
+ # do NOT do this!
+ clobber:
+ -git clean -f # WRONG !!!And do NOT use git for any other Makefile rule either.
NOTE: mkiocccentry(1) will directly run make clobber in the submission
+directory. And although it is not an error if this fails, if it fails because the
+Makefile does not have a clobber rule, it will be flagged by mkiocccentry(1)
+(you may ignore this but it does put you at a risk of violating the rules).
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All Rights Reserved. Permission for personal, education or non-profit use is granted provided this this copyright and notice are included in its entirety and remains unaltered. All other uses must receive prior permission in writing by contacting the judges.
-Jump to: top
-Be sure to read the IOCCC rules.
+The markdown form of these guidelines is available for download.
-IMPORTANT: Be SURE to read the IOCCC rules.
-Jump to: top
-Most lines (we sometimes make mistakes) that were modified since the previous -IOCCC start with a solid 4 pixel black left border (or, in the case of a code -block or blockquote, just a vertical bar).
-Jump to: top
-This file contains guidelines intended to help people who wish to -participate in the International Obfuscated C Code Contest -(IOCCC).
-These are NOT the IOCCC rules, though it does contain comments -about them. The IOCCC guidelines should be viewed as -hints and suggestions. Submission that violate the -guidelines but remain within the rules are -allowed. Even so, you are safer if you remain within the IOCCC -guidelines.
-Of course if a guideline is talking about a rule and you break that guideline, -you stand a good chance of having your submission rejected for breaking the -rule, not the guideline.
-You SHOULD read the CURRENT IOCCC rules, prior to submitting -code to the contest.
-Jump to: top
-IMPORTANT NOTE: Until the contest enters the open state, any or all -of the above dates and times may change AT ANY TIME!
- -Until the contest status becomes open, -the IOCCC rules, -IOCCC guidelines and the tools in the -mkiocccentry repo SHOULD be -considered provisional BETA versions and may be adjusted AT ANY TIME -before the contest status becomes open.
-See the -FAQ on “how to register and submit to the IOCCC” -for instructions on registering and participating in the IOCCC, as the process -may change from contest to contest.
-To assist in the formation of the xz compressed tarball for submission, use the
-mkiocccentry(1) tool as found in the mkiocccentry repo.
See FAQs regarding:
-Uploading a tarball not formed by mkiocccentry(1) puts you at a very big risk of
-violating
-Rule 17 - Packaging,
-especially as mkiocccentry(1) does a
-great number of things that are required, and it also runs many checks, and if
-any of those checks fail, you are at a very great risk of having your submission
-rejected for violating
-Rule 17 - Packaging.
We STRONGLY recommend you do install the -mkiocccentry toolkit.
-IMPORTANT NOTE: the tools that require other tools, mkiocccentry(1) and
-txzchk(1), will, as of version 2.0.2 2025-03-11, search under $PATH. If
-you have an earlier version and you have not installed the tools and run the
-tools from outside the repo directory, you will have to use the options to the
-tools to set the path to the required tools.
See the -FAQ on “obtaining and compiling the most recent mkiocccentry tools” -and the -FAQ on “how to enter the IOCCC” -as that FAQ has important details on -how to register -as well as -how to upload your submission to the IOCCC.
-While the contest is open, you may modify your
-previously uploaded submission by rebuilding your submission with the
-mkiocccentry(1) tool and then re-uploading it to the same slot number on the
-submit server.
HINT: so that you do not have to repeatedly answer all the
-questions, the mkiocccentry(1) tool has the options -a answers, -A answers
-and -i answers, where -a will write to an answers file (if it does not
-already exist), -A WILL OVERWRITE THE FILE and -i will read the answers from
-the file. If you use -A, BE SURE you don’t overwrite another file by accident!
Be aware that even with the -i answers you will still be required to confirm
-most if not all y/n questions - you just don’t have to input the name of the
-submission, the abstract, the author details etc. If you really wish to
-circumvent this you can use the -Y option but we do not recommend this because
-if your update breaks a rule or there is some problem, you might not see it.
To help with not having to repeatedly enter a UUID, whether for the same
-submission or multiple submissions, you can use the -u uuidfile or -U UUID
-option. See the
-FAQ on “how to avoid re-entering your UUID”
-for more details. Note that the -i answers option cannot be used with the UUID
-options as the answers file includes the UUID.
The overall size limit (see Rule 2a Gross Size](rules.html#rule-2a-gross-size)) on prog.c has been
-increased from 4096 to 4993 bytes.
-The Rule 2b Next Sizesize was changed from
-4096 to 4993 to keep the “2b to 2a” size ratio to a
-value similar to the 2001-2012 and
-2013-2020 IOCCC eras.
The Rule 2b Next Size size has increased from 2053 to 2503 -bytes.
- --+You should pay attention to our observations on +code size and Rule 2 remarks for IOCCC28.IMPORTANT HINT: Only 3 of the 23 IOCCC28 winners came close to the -Rule 2 - Size limit. -Large code size isn’t -everything. :-) Those submitting to future contents should take a careful -note of that fact.
-
Your submission must satisfy BOTH the maximum size
Rule 2a Gross Size
@@ -648,1193 +517,66 @@ preprocessor keywords) as 1. The size tool counts all other bytes as 1
excluding ASCII whitespace, and excluding any ‘;’, ‘{’ or ‘}’ followed by
ASCII whitespace, and excluding any ‘;’, ‘{’ or ‘}’ byte immediately
before the end of file.
ASCII whitespace includes ASCII tab, ASCII space, ASCII newline, -ASCII formfeed, and ASCII carriage return.
+ASCII whitespace includes ASCII tab, ASCII space, ASCII newline, ASCII formfeed, and ASCII carriage return.
When ‘;’, ‘{’ or ‘}’ are within a C string, they may still not be
-counted by the IOCCC size tool. This is a feature, not a bug!
In cases where the above summary and the algorithm implemented by
the IOCCC size tool iocccsize(1) conflict, the algorithm implemented
by the current version of iocccsize(1) is preferred by the IOCCC judges.
In other words, make sure iocccsize does not flag any issues with your
-prog.c.
There are at least 2 other reasons for selecting 2503 as the 2nd limit besides -the fact that 2503 is a prime. These reasons may be searched for and discovered -if you are “Curios!” about 2503. -:-) Moreover, 2053 was the number of the kernel disk pack of one of the judge’s -BESM-6, and 2503 is a decimal anagram of 2053.
-Take note that this secondary limit imposed by the IOCCC size tool
-obviates some of the need to #define C reserved words in an effort
+
Make sure iocccsize does not flag any issues with your prog.c.
There a much less need to #define C reserved words in an effort
to get around the size limits of
-Rule 2 - Size.
Yes Virginia, that is a hint!
-The official locale of the IOCCC is C.
- -The mkiocccentry toolkit, -as of Release version 2.4.4 2025-03-15, -will run with a locale set to C. - +Rule 2 - Size +because of theiocccsize(1) algorithm.
+Yes Virginia, the previous guideline sentence is an important hint!
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-You are encouraged to examine the winners of previous contests.
-Keep in mind that rules change from year to year, so some winning -entries might not be valid submissions this year; what was unique -and novel one year might be ‘old’ the next year.
-A submission is usually examined in a number of ways. We typically apply -a number of tests to a submission:
+See FAQ on “What is an author handle?”.
+Jump to: top
+While it is NOT required, you are allowed to use tools or services such as:
#include lines#define and #include linesYou should consider how your submission looks in each of the above tests. -You should ask yourself if your submission remains obscure after it has been -‘cleaned up’ by the C pre-processor and a C beautifier.
-Your submission need not pass all of the above tests. In certain -cases, a test is not important. Submissions that compete for the -‘strangest/most creative source layout’ need not do as well as -others in terms of their algorithm. On the other hand, given -two such submissions, we are more inclined to pick the submission that -does something interesting when it’s executed.
-We try to avoid limiting creativity in our rules. As such, we -leave the contest open for creative rule interpretation. As in real -life programming, interpreting a -requirements document or a customer request is important. For this reason, we -often award ‘Best abuse of the rules’ or ‘Worst abuse of the -rules’ or some variation to a submission that illustrates this -point in an ironic way.
The IOCCC has a rich history of remarkable winning entries created by -authors who skillfully employed various techniques to develop their code. -While it is NOT required, you are allowed to use tools to develop -and test your submission. These tools may include, but are not limited -to code generators, code analysis tools, static code analysis tools, -runtime analysis tools, machine learning tools, natural language models, -code copilot tools, so-called AI services, large language models (LLMS), etc. -If you do make use of such tools or services, then we ENCOURAGE you to describe +authors who skillfully employed various techniques to develop their code.
+If you do make use of such tools or services, then we ENCOURAGE you to describe
how you used such tools in your remarks.md file.
You may use git, or services such as GitHub -to develop and maintain your submission. However, we DISLIKE -submissions that require them in order to build/compile your submission.
-Submissions will be judged in an environment that has no IDE. -Any submission that fails to compile/build because it requires -an IDE will be rejected.
-We will use the make(1) tool, your Makefile, and other tools found in
-Single UNIX Specification
-environments and systems that conform to the Single UNIX
-Specification
-in the building and compiling of your submission.
We do realize that there are holes in the rules, and invite -submitters to attempt to exploit them. We may award ‘Worst abuse of the -rules’ or ‘Best abuse of the rules’ or some -variation and then plug the hole next year.
-When we do need to plug a hole in the IOCCC rules or IOCCC -guidelines, we will attempt to use a very small plug, if not -smaller. Or, maybe not. :-)
-There may be fewer than 2^7+1 reasons why these IOCCC -guidelines seem obfuscated.
-IMPORTANT: Be sure that your submission works as documented in your
-remarks.md file. We sometimes make an effort to debug a submission
-that has a slight problem, particularly in or near the final round.
-On the other hand, we have seen some otherwise excellent submissions
-fall down because they didn’t work as documented.
If you submission has bugs and/or mis-features, you are MUCH BETTER off
-documenting such bugs and/or mis-features in your remarks.md file.
Consider an example of a prime number
-printing program that claims that 16 is a prime number.
-Noting such a bug in your remarks.md file could save your submission:
--“this submission sometimes prints the 4th power of a prime by mistake”
-
Sometimes a strange bug or (mis-)feature can even help the submission! Of course, a correctly -working submission might be better.
-We tend to look down on a prime
-number printer that claims that
-16 is a prime number.
-Clever people will note that 16 might be prime
-under certain conditions. ;-) Wise people, when submitting something clever
-will fully explain such cleverness in their submission’s remarks.md file.
People who are considering to just use some complex mathematical -function or state machine to spell out something such as “hello, -world!” really really, and we do mean REALLY, do need to be more creative.
-Ultra-obfuscated programs are, in some cases, easier to -deobfuscate than subtly-obfuscated programs. Consider using -misleading or subtle tricks layered on top of or under an -appropriate level of obfuscation. A clean looking program with -misleading comments and variable names might be a VERY GOOD START -to a great submission!
+In short: You created it, you own it, and its an original work, or you have explicit permission.
+See FAQ on “May I use AI, LLM, Virtual coding assistants, or similar tools to write my submission?”.
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-mkiocccentryRule 17 - Packaging
-(the mkiocccentry(1) rule) states that
-you REALLY SHOULD use the mkiocccentry(1) tool to package your submission tarball.
See the mkiocccentry repo
-for the mkiocccentry(1) tool and below for more details.
IMPORTANT NOTE: make CERTAIN you have the most recent version of the
-mkiocccentry toolkit! See the
-FAQ on “obtaining the mkiocccentry toolkit”.
mkiocccentry runs a number of checks, by the tool itself and by executing
-other tools, before packaging your xz compressed tarball, including running
-chksubmit(1) on the submission directory.
If mkiocccentry encounters an error, the program will exit and the xz
-compressed tarball will not be formed. For instance, if
-chksubmit fails to validate the submission directory, either because
-of a validation error in the .auth.json or .info.json
-JSON files or because of
-something else that mkiocccentry(1) creates or does, it is an
-error and possibly a bug that you should report as a bug at the
-mkiocccentry bug report
-page.
-PLEASE run the bug_report.sh script to help us out here! See the
-FAQ on “reporting mkiocccentry bugs”.
Once the tarball is packaged it will
-run txzchk(1), which will also run fnamchk(1), as part of its algorithm.
However, even if mkiocccentry or one of the tools it invokes reports an error,
-it does not necessarily mean it is a bug in the code. It might be an issue with
-your submission. Thus if you report an error as a bug it might not be something
-that will be fixed as there might not be anything wrong with the tools.
On the other hand, some conditions flagged by mkiocccentry(1) are warnings
-and it allows you to override these, if you wish. If you’re brave enough you can
-use the -W option to ignore all warnings but this is a big risk; the -y
-option will assume ‘yes’ to most questions but this is also a big risk. Using
--Y will say ‘yes’ to even more prompts. Needless to say, we do NOT
-recommend these options.
In many places it will prompt you to verify what you input, allowing you to -correct details as you go along. Be advised that there is a default answer and -if you press enter it will proceed with that default, so make sure you have -provided the correct answer.
-If you wish to test that your submission passes the mkiocccentry(1) tests
-without having to type in in answers each time, you can use the -d or -s seed
-option to mkiocccentry for the tool to pseudo-randomly create answers for you.
-For example:
mkiocccentry -d workdir topdirIMPORTANT NOTE: if you run an IOCCC related tool outside the repo directory
-(specifying the absolute or relative path to the tool) and you have not
-installed the tools (and we STRONGLY recommend you do install them),
-then you will have to specify the options (such as paths) for the tools that are required like
-chksubmit(1), txzchk(1) and fnamchk(1).
Make sure you have -the latest version of of the mkiocccentry toolkit -so that you do not violate -Rule 17 - Packaging -by mistake.
-Jump to: top
-mkiocccentry(1) synopsisThe synopsis of the mkiocccentry(1) tool is:
mkiocccentry [options] workdir topdirTo help you with editing a submission, the mkiocccentry(1) tool has
-some options to write OR read from an answers file so you do not have to input
-the information about the author(s) and the submission more than once, unless of
-course you need to make some changes, in which case you can use the option that
-overwrites the file. If you do use the overwrite option, MAKE SURE you do
-not overwrite another file!
See the -FAQ on the -“mkiocccentry tool” -for how to use this tool and the -FAQ on the -“finer details of mkiocccentry” -for even more information.
-The mkiocccentry(1) tool will execute a number of tools, some of which will
-execute one or more additional tools.
iocccsizemkiocccentry(1) will use code from iocccsize(1) which detects a number of
-issues (such as Rule 2 - Size) that you may ignore, if you wish, as
-noted above.
In other words, you no longer need to run iocccsize manually. However, the
-checks described above are still made but through the mkiocccentry(1) tool itself.
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-chksubmitmkiocccentry(1) will write two JSON files: .auth.json and
-.info.json. These files contain information about the author(s) and about the
-submission. After these files are formed, the chksubmit(1) tool will be run on
-the submission directory; this tool not only validates the two JSON files
-(and runs specific checks on them after validating the JSON), but it also
-verifies that what is in the manifest in .info.json matches the contents of
-the directory, in addition to other checks. If chksubmit(1) fails to validate
-anything at all, your submission WILL BE rejected!
IMPORTANT: although chksubmit(1) validates the files in the directory, it
-only inspects the contents of the two JSON files; it performs other kinds of
-checks on the other files, and those checks are run on the two JSON files as
-well.
If you submit your own JSON files (other than .auth.json and
-.info.json) then they do NOT have to be valid JSON.
-However, if you do provide such invalid JSON files, PLEASE
-document and explain this in your remarks.md file.
If chksubmit does not pass and you used mkiocccentry(1) it is very likely a
-bug and you should report it as a bug at the mkiocccentry issues
-page.
-PLEASE run the command:
make bug_reportfrom the top level repo directory itself and attach the bug report file (it will -tell you the name of the file). See also the -FAQ on “reporting mkiocccentry bugs”.
-Assuming that chksubmit(1) successfully validates your submission directory,
-the tarball will be formed and then txzchk(1) will be executed on it. In this
-case, there should be no problems, as mkiocccentry(1) should NOT form a
-tarball if there are any issues.
If mkiocccentry(1) is used and chksubmit(1) fails to validate your submission
-directory, then unless it is a system specific problem, it could be a bug in
-mkiocccentry(1), chksubmit(1) or possibly jparse, although this is unlikely.
-Nonetheless, if you believe there is a bug, you may report it as explained above.
If you want to know what .auth.json is, see the
-FAQ on “.auth.json”.
-If you want to know what the .info.json file is, see the
-FAQ on “.info.json”.
-On the other hand, if you want to know a bit more details about chksubmit(1), see the
-FAQ about “chksubmit”.
chksubmit uses the jparse library. See the
-jparse
-README.md
-in the mkiocccentry GitHub repo subdirectory
-jparse as well as
-the jparse library README.md
-file
-in the mkiocccentry GitHub repo subdirectory
-jparse, for more
-details.
The jparse parser, library and tools were co-developed by Cody Boone
-Ferguson and Landon Curt
-Noll in 2022-2025 and come from the
-jparse repo. However, the mkiocccentry
-tools use a clone of the jparse repo at
-a specific release. Thus the mkiocccentry will at times be behind the
-jparse repo!
You do NOT need to install jparse from the jparse
-repo! The mkiocccentry tools link in the
-static library from mkiocccentry’s clone.
The mkiocccentry toolkit also has a clone of both the dbg
-library and the
-dyn_array library; the dyn_array
-library uses the dbg
-library and the jparse
-library uses both libraries but unlike in the
-jparse repo, the libraries do not need to be
-installed separately, in order to use the tools in mkiocccentry.
In other words, mkiocccentry contains everything you need, and even if you
-do install the libraries from their respective repos, it/they will not be
-used when compiling the mkiocccentry tools. This is important to
-make sure that you’re using the correct versions, which is also verified by
-chksubmit (in the JSON files created by mkiocccentry(1)). See
-Rule 17 - Packaging!
Please see the
-FAQ on “validating your submission directory
-for more details on chksubmit(1).
You might also wish to see the -FAQ on “.auth.json” -and the -FAQ on “.info.json” -for much more information on these files.
-Jump to: top
-txzchktxzchk(1) performs a wide number of sanity checks on the xz compressed
-tarball; if any issues are found (‘feathers are stuck in the tarball’ :-) )
-AND if and ONLY IF you used mkiocccentry(1), then it is possibly a
-bug in one of the tools and you might want to report it as a bug at the
-mkiocccentry bug report
-page.
-PLEASE run the bug_report.sh script to help us out here! You may do this
-by running from the top level directory of the repo make bug_report. See the
-FAQ on “reporting mkiocccentry bugs”.
As part of its algorithm, txzchk(1) will run fnamchk(1) on the
-tarball to verify that the filename is valid. See the
-FAQ on “fnamchk”
-and the fnamchk section below for more details on this tool.
It is beyond the scope of this document to discuss the many tests that
-txzchk(1) performs; if you wish to know, we refer you to the source
-code or the man
-page. You might just find a fun option if you do either of these!
Of course, as txzchk does not extract the tarball, it is possible that if you
-manually package your submission tarball and/or find and exploit a missing
-check, you could still be violating
-Rule 17 - Packaging.
If you use an optional filename for something other than their intended use -in order to get past the file limit, we will consider that an -abuse of rules.
- - - - -If you DO include a tarball, and the build process or the program extracts
-said tarball(s), the make clobber rule MUST remove the extracted files.
IMPORTANT REMINDER: make SURE your tarball does NOT reveal who you are!
-The mkiocccentry(1) tool creates a v7 format tarball to prevent this. You can
-do the same like:
tar --format=v7 -cJf foo.txz directorySee -Rule 17 - Packaging -and also the -FAQ on “maximum number of files”.
-If you do not follow these points, you -are at a great risk of violating -Rule 17 - Packaging!
-NOTE: if you want to include a test-suite that requires a lot of files,
-please suggest this in your remarks.md and if your submission wins it can
-be done. In other words you should NOT use a tarball for a test-suite unless you
-have a very good reason for this (and if you do, make SURE you specify why
-in your remarks.md file).
See also the -FAQ on “txzchk”.
-Jump to: top
-fnamchk(1)As an important part of its algorithm, txzchk(1) directly executes
-fnamchk(1). If the filename is invalid (or the filename does not match the
-directory name of the tarball) then it is an error and you risk violating
-Rule 17 - Packaging.
-Nevertheless, you can run the tool manually,
-should you wish to.
For more information on fnamchk and how to manually validate your submission
-tarball filename, see the
-FAQ on “fnamchk”.
It is extremely unlikely that fnamchk(1) reporting an invalid filename is a
-bug in fnamchk(1) and as such, ignoring such an issue risks violating
-Rule 17 - Packaging
-which is a big risk. Of course, using mkiocccentry(1)
-would prevent this from happening as it would not create such a file anyway. If
-mkiocccentry(1) was used it would rather suggest a bug in one of the tools and
-you should report it as a bug at the mkiocccentry issues
-page.
-See the
-FAQ on “reporting mkiocccentry bugs”.
As you can see, the use of mkiocccentry(1) is HIGHLY RECOMMENDED, and at
-the risk of stating the obvious, you run A VERY BIG RISK of having
-your submission rejected if you package your own tarball, and there are ANY
-problems. For instance, if chksubmit(1) found a problem in your .info.json
-file, the mkiocccentry(1) tool would not package it. But if you were to package
-it manually, you would be violating
-Rule 17 - Packaging.
-But even if
-everything checks out OK you should NOT assume that everything IS OK.
Although the tools have been tested extensively, it is nonetheless possible for bugs to -exist in the code, as all programmers know. In this case, please ask for help or report what -you think is a bug via the bug report issues page in the mkiocccentry -repo.
-Of course, it is also possible for mkiocccentry(1), or one or more of the
-tools it executes (or another tool executes), to fail, but NOT because of a
-bug. An example problem is if there is not enough memory available or if some
-other library or syscall fails. Nonetheless it might be worth reporting as a
-bug; it is a judgement call: if it’s a bug it’ll be addressed and if it’s not
-that’s OK too!
We recommend AND encourage you to use the example Makefile,
-as the starting point for your submission’s required Makefile:
Feel free to modify the Makefile to suit your obfuscation
-needs.
Please add a space between the = and the value of variables, in the
-Makefile, making sure that the = comes immediately after the name. See the
-example Makefile for examples.
The rest of this section and its subsections will assume that you are using some
-variant of the example Makefile, again renamed as Makefile.
We suggest that you compile your submission with a commonly available
--std=gnu17 (ISO C 2017 with GNU extensions) C compiler, via clang(1)
-and/or gcc(1).
Unless you clearly state otherwise in your remarks.md file, AND put in
-your submission’s Makefile, we will compile using -std=gnu17 -O3!
It is OK if you need to require your submission to NOT be compiled
-using the default -std=gnu17 -O3 settings. Simply explain why
-your submission should NOT be compiled using -std=gnu17 -O3 in
-your remarks.md file, AND adjust your Makefile accordingly.
One reason that you might have to change the flags, is that the optimiser is
-known to break some programs, but there are certainly other possible valid
-reasons. Again, just update the Makefile and explain it in your remarks.md.
-See the optimiser section for details for changing optimiser
-flags.
For more fun when it comes to optimisers breaking code, see -1986/marshall/compilers.html.
-IMPORTANT NOTE: The use of -std=gnu17 does NOT imply the use of the gcc
-compiler! We often start by compiling using the clang C compiler instead.
PLEASE NOTE: in macOS, the compiler gcc found at /usr/bin/gcc is
-in truth the clang compiler, as /usr/bin/gcc --version will show!
You may change the standard under which your submission is compiled
-by modifying the CSTD Makefile variable. For example, to use c99 instead:
CSTD= -std=c99You may change the level of optimization and compiler debug level
-that your submission is compiled with, by modifying the OPT Makefile variable.
-For example, to compile without optimization, and to include debug symbols:
OPT= -O0 -g3The default warning flags are set via the CWARN variable, as shown in the
-example Makefile:
# Common C compiler warning flags
- #
- CWARN= -Wall -Wextra ${CSILENCE} ${CUNKNOWN}For details on CSILENCE and CUNKNOWN, see the section on disabling
-warnings.
-Weverything optionFor compilers, such as clang, that have the -Weverything option,
-while you may wish to try it, you should read our
-FAQ on “clang -Weverything”.
-We do NOT recommend that you put
-the use of -Weverything into your submission’s Makefile for the reasons
-cited there. This goes even if your version does not trigger a warning as some
-other version might!
On the other hand, if ${CC} has “clang” in the name, the example Makefile will
-automatically enable -Weverything, so you might have to use -Wno-foo
-options anyway, as detailed below. See the
-FAQ on “-Weverything”
-for more details.
If “clang” is NOT in ${CC}, the CWARN variable will not be further
-modified.
There is no real penalty for compiler warnings. Sometimes -compiler warnings cannot be helped: especially in the case of -obfuscated C. :-) So if you cannot easily get rid of a compiler -warning, try not to fret too much.
-We LIKE code that has a minimum of warnings, especially under the
-more strict -Wall -Wextra -pedantic mode:
CWARN= -Wall -Wextra -pedanticThe two previous guidelines might be thought by some as being somewhat -contradictory. Isn’t life, and isn’t trying to satisfy “contradictory customer -requirements” all too often like that? :-) Try to minimize warnings if you -can.
-If you manage to produce very few warnings, or perhaps no warnings at
-all under the -Wall -Wextra -pedantic mode, then by all means brag about it in
-your remarks.md file AND BE SURE TO TELL US the OS, OS version, compiler
-and compiler version in which you observed this occurring (in case our OS and
-compiler produces a different result: so your submission won’t be penalized for
-not meeting your claims).
On the other hand, some warnings cannot be disabled and are enabled by compilers -without any warning option specified. These are sometimes inevitable in -obfuscated code and even in some non-obfuscated code, and you should not worry -about this, though it might be worth pointing out.
-For instance, some compilers like to warn about use of pointers as arrays, which seems to
-be dubious, as it obviously can’t (always) be avoided, being a big part of C, so
-you should not worry about this either; this is the warning
--Wunsafe-buffer-usage and the way to disable it is -Wno-unsafe-buffer-usage.
-See also the
-FAQ on “forced warnings”
-and the
-FAQ on “-Weverything”.
If your submission issues lots of warnings but is otherwise
-marvelously obfuscated in multiple levels, don’t worry about it. Nevertheless,
-be sure that the warnings do not constitute a potential “show stopper”
-compiler problem. Be sure that compilers such as both gcc and clang won’t
-produce a compiler error and refuse to compile your code: unless for some
-reason that is what you intend to happen in which case document that too in your
-remarks.md file. :-)
All other things being equal, a program that must turn off fewer -warnings will be considered better, for certain values of better.
-To turn off a compiler warning, in your submission’s Makefile,
-try something such as:
CSILENCE= -Wno-some-thing -Wno-another-thing CSILENCE= -Wno-parentheses -Wno-binding-in-condition -Wno-misleading-indentationIf you need to define something on the compile line, use
-the CDEFINE Makefile variable. For example:
CDEFINE= -Dfoo -Dbar=bazNOTE: just because we offer a default way to use the -D option, we still
-do not like excess use of -D to get past size limits, especially since you
-could use #define in your code instead.
If you need to include a file (as in #include) on the command line, use the
-CINCLUDE Makefile variable. For example:
CINCLUDE= -include stdio.hIf you need to add other “magic” flags to your compile line,
-use the COTHER Makefile variable. For example:
COTHER= -fno-math-errnoNOTE: We only recommend using “magic” flags if BOTH gcc
-and clang support it.
Again, please note that in macOS, /usr/bin/gcc is actually clang!
When make clobber is invoked, we request that submissions be restored
-to their original submission state. For example, any temporary files
-(including the compiled program(s)) created during the build process, or
-during execution should be removed by the clobber rule. In other words, the
-only things that should be in the directory after running make clobber is what
-is in your submission tarball itself.
While people are free to manage their submission under git(1) or even use a
-GitHub repo, dot-files and dot-directories such as .git are not allowed in a
-submission.
The mkiocccentry(1) tool will ignore dot-files and dot-directories (such as
-.vimrc, .bashrc, .git and .github) and not put them in the submission’s
-compressed tarball. So while you may use such files and
-directories to help develop your submission, they won’t be included when you run
-the mkiocccentry(1) tool.
Even if you did manage to get dot files or dot directories in the tarball
-somehow, txzchk(1) will flag it as an error. When the judges run txzchk(1)
-on the uploaded submission compressed tarball, if anything is wrong, for
-instance if you “sneak in” any dot files or dot directories, the submission
-WILL BE REJECTED for violating
-Rule 17 - Packaging!
You may use whatever tools you need to develop your submission, including the
-use of git(1) or gh(1), just be sure that your submission code and your
-submission Makefile don’t depend on such tools.
Of course if you do use GitHub to work on your submission, you might want to -make the repo private so you don’t reveal who you are. :-)
- - -In other words, for make clobber, do something like:
clobber:
- ${RM} -f foo bar bazand NOT something like this:
- # do NOT do this!
- clobber:
- -git clean -f # WRONG !!!And do NOT use git for any other Makefile rule either.
NOTE: mkiocccentry(1) will directly run make clobber in the submission
-directory. And although it is not an error if this fails, if it fails because the
-Makefile does not have a clobber rule, it will be flagged by mkiocccentry(1)
-(you may ignore this but it does put you at a risk of violating the rules).
Jump to: top
-We VERY MUCH LIKE submissions that use an edited variant of the
-example Makefile, as described and linked to in the Makefile section,
-renamed as Makefile of course. This makes it easier for the IOCCC judges
-to test your submission. And if your submissions wins, it makes it easier to integrate it into
-the Official IOCCC winner website.
We VERY MUCH LIKE submissions that have some educational value. This does NOT mean
-that your submission should not be obfuscated but rather that the IOCCC has moved away from
-the idea of “spoilers”. You should not encrypt or rot13 content in your remarks.md file.
It is VERY MUCH appreciated if your remarks have some educational -value. And although educational value is not required, it is an -EXCELLENT bonus.
-We LIKE submissions that use an edited version of the
-try.sh example script (and if you have alternate code,
-the same applies with the try.alt.sh script):
Of course, it is quite possible that only one invocation is -possible, so it is not necessarily detrimental to your submission if you do not -include one, though we do like interesting and creative uses of submissions. See -also the -FAQ on “submitting try.sh and try.alt.sh scripts”.
- - - - -Doing masses of #defines to obscure the source has become ‘old’. We
-tend to ‘see thru’ masses of #defines due to our pre-processor tests
-that we apply. Simply abusing #defines or -Dfoo=bar won’t go as far
-as a program that is more well rounded in confusion.
Many C compilers DISLIKE the following code, and so do we:
- #define d define
- #d foo /* <-- don't expect this to turn into #define foo */In other words, it is a compilation error, and in order to get older -IOCCC winning entries that did this to compile, we had to update them to not do this.
-When declaring local or global variables, you should declare the type:
- int this_is_fine;
- this_is_not; /* <-- Try to avoid implicit type declarations */We tend to like less a submission that requires either
-gcc OR clang. We prefer submissions that can compile
-under BOTH gcc AND clang. Hint!
We RECOMMEND that the compiler flags you use in your
-submission’s Makefile are supported by BOTH gcc AND clang.
We DISLIKE the use of obscure compiler flags, especially
-if gcc and/or clang do not support it. We suggest
-that you not use any really obscure compiler flags if you can help it.
One side effect of the above is that you cannot assume the use -of nested functions such as:
- int main() {
-| void please_dont_submit_this() {
-| printf("The machine that goes BING!!\n");
- }
-| please_dont_submit_this();
- }On 2012 July 20, the IOCCC judges rescinded the encouragement of
-nested functions. Such constructions, while interesting and sometimes
-amusing, will have to wait until they are required by a C standard that are
-actually implemented in BOTH gcc AND clang.
We DISLIKE submissions that require the use of -fnested-functions.
We prefer programs that do not require a fish license: crayons and -cat detector vans not withstanding.
-If your submission uses functions that have a variable number of
-arguments, be careful. Systems implement va_list in a wide variety
-of ways. Because of this, a number of operations using va_list are
-not portable and must not be used:
va_list variable to/from a va_list variableva_list variable into/from a va_list variableva_list variable to a function expecting a non-va_list argva_list variable to a function expecting a va_list argva_list variablesva_list as a structure or unionIn particular, do not treat va_list variables as if they were a char **.
We DISLIKE the use of varargs.h. Use stdarg.h instead.
We DISLIKE the use of gets(3). Use fgets(3) instead.
We tend to DISLIKE the blatant use of tarballs in an attempt to simply get
-around the extra file number limit. We realize there may be cases where a
-tarball containing a number of extra files may be needed. Such a need for a
-tarball MUST be explained in the remarks.md file.
On 28 January 2007, the Judges rescinded the requirement that the
-# in a C preprocessor directive must be the 1st non-whitespace byte.
The exit(3) function returns void. Some broken systems have exit(3)
-return int; your submission should assume that exit(3) returns a void.
Small programs are best when they are short, obscure and concise. -While such programs are not as complex as other winners, they do -serve a useful purpose: they are often the only program that people -attempt to completely understand. For this reason, we look for -programs that are compact, and are instructional.
-While those who are used to temperatures found on dwarf -planets -(yes Virginia, dwarf planets ARE planets!), such as -Pluto, might be able to -explain to the Walrus why our seas are boiling hot, the question of -whether pigs have wings is likely to remain a debatable point to most.
-One line programs should be short one line programs: say around 80 to 132 -bytes long. Going well beyond 132 bytes is a bit too long to be called -a one-liner in our vague opinion.
-We tend to DISLIKE programs that:
-index(3)/strchr(3) differences are OK, but
-sockets/streams specific code is likely not to be)remarks.md file)In order to encourage submission portability, we DISLIKE submissions that -fail to build unless one is using an IDE. For example, do not -mandate that one must use Microsoft Visual Studio to compile -your submission.
-The program must compile and link cleanly in a Single UNIX -Specification -environment. Therefore do not assume the system has a -windows.h include file:
- #include <windows.h> /* we DISLIKE this */Unless you are cramped for space, or unless you are entering the -‘Best one liner’ category, we suggest that you format your program -in a more creative way than simply forming excessively long lines.
-At least one judge prefers to maintain the use of the -leap-second -as part of the world’s time standard. If your code prints time -with seconds, we prefer that your code be capable of printing the -time of day during a leap-second where the value in seconds -after the minute mark is 60.
-The Makefile should not be used to try and get around the size limit. It is
-one thing to make use of a several -Ds on the compile line to help out, but it
-is quite another to use many bytes of -Ds in order to try and squeeze the
-source under the size limit.
Your source code, post-pre-processing, should not exceed the size of -Microsoft Windows. :-)
-Other windows, on the other hand, might be OK: especially where “X -marks the spot”. Yet on the third hand, windows are best when they are -“unseen” (i.e., not dirty). :-)
-The IOCCC judges, as a group, have a history giving wide degree of latitude -to reasonable submissions. And recently they have had as much longitudinal -variation as it is possible to have on Earth. :-)
-You should try to restrict commands used in the build file to commands found in -Single UNIX -Specification -environments and systems that conform to the Single UNIX -Specification.
-You may compile and use your own programs. If you do, try to build and execute -from the current directory. This restriction is not a hard and -absolute one. The intent is to ensure that the building of your -program is reasonably portable.
-We prefer programs that are portable across a wide variety of UNIX-like -operating systems (e.g., Linux, GNU Hurd, BSD, UNIX, etc.).
---You are in a maze of twisty guidelines, all different.
-
There are at least zero IOCCC judges who think that -Fideism has little -or nothing to do with the IOCCC judging process.
-Don’t forget that the building of your program should be done -WITHOUT human intervention. So don’t do things such as:
- prog: prog.c
- #echo this next line requires data from standard input
- cat > prog.c
- ${CC} prog.c -o progHowever, you can do something cute such as making your program
-do something dumb (or cute) when it is built ‘automatically’, and
-when it is run with a human involved, do something more clever.
-For example, one could put in their Makefile:
prog: prog.c
- ${CC} prog.c -DNON_HUMAN_COMPILE -o prog
- @echo "See remarks section about alternate ways to compile"and then include special notes in your remarks.md file for
-alternate / human intervention based building.
We want to get away from source that is simply a compact blob of -bytes. REALLY TRY to be more creative than blob coding. HINT!
-Please do not use things like gzip(1) to get around the size limit.
-Please try to be much more creative.
We really DISLIKE submissions that make blatant use of including -large data files to get around the source code size limit.
- -Did we remember to indicate that programs that blatantly use -some complex state machine to do something simple, are boring? -We think we did. :-)
---All generalizations are false, including this one. – Mark Twain
-
Given two versions of the same program, one that is a compact blob -of code, and the other that is formatted more like a typical C -program, we tend to favor the second version. Of course, a third -version of the same program that is formatted in an interesting -and/or obfuscated way, would definitely win over the first two! -Remember, you can submit more than one submission. See the -IOCCC rules -for details (in particular, -Rule 8 - Submission).
-We suggest that you avoid trying for the ‘smallest self-replicating’ -source. The smallest, a zero byte entry, won in -1994.
-Programs that claim to be the smallest C source that does something, really -better be the smallest such program or they risk being rejected because -they do not work as documented.
-Please note that the C source below, besides lacking in obfuscation, -is NOT the smallest C source file that when compiled and run, dumps core:
- main;Unless you specify -fwritable-strings (see COTHER in the example
-Makefile, described in the Makefile section), do not assume this
-sort of code will work:
char *T = "So many primes, so little time!";
- ...
- T[14] = ';'; /* modifying a string requires: -fwritable-strings */Even so, one should probably not assume that this is universally accepted.
-Initialized char arrays are OK to write over. For instance, this is OK:
- char b[] = "Is this OK";
- b[9] = 'k'; /* modifying an initialized char array is OK */There are more than 1 typos in this very sentence.
-X client submissions should be as portable as possible. Submissions that -adapt to a wide collection of environments will be favored. For -example, don’t depend on a particular type or size of display. -Don’t assume the use of a particular browser. Instead assume a -generic browser that forms to a widely used W3C -standard. -Don’t assume a particular sound sub-system or video driver is installed -in the OS. Instead, make use of a well known and widely available open -source program (one that actually works) to display audio/visual data.
-X client submissions should avoid using X related libraries and -software that are not in wide spread use.
-As of Red Hat RHEL9.0, the X.org server is deprecated. See the -FAQ on “Xorg deprecation”” -for more details. This does not mean that a submission using this will -necessarily be rejected, but it would be better if it can support Wayland in -some way or another.
-This could be the only guideline that contains the word -fizzbin.
-However, do you know how to play fizzbin? -You do?!? (Except on Tuesday?)
-OK, there are actually 2 guidelines that contain the word -fizzbin, -unless you count this one, in which case there are 3. :-)
-We DISLIKE submissions that use proprietary toolkits such as the M*tif,
-Xv*ew, or OpenL*ok toolkits, since not everyone has them. Use an
-open source toolkit that is widely and freely available instead.
NOTE: The previous guideline in this spot has been replaced by this guideline:
-X client submissions should try to not to depend on particular items in
-.Xdefaults. If you must do so, be sure to note the required lines
-in the your remarks.md file. They should also not depend on any
-particular window manager.
Try to avoid submissions that play music that some people believe is copyrighted -music.
-While we recognize that UNIX is not a universal operating system, the contest -does have a bias towards such systems. In an effort to expand the scope of the -contest, we phrase our bias to favor the Single UNIX -Specification.
-You are well advised to submit code that conforms to the Single UNIX -Specification Version 4.
-To quote the IOCCC judges:
---You very well might not be completely prohibited from failing to not partly -misunderstand this particular guideline, but of course, we could not possibly -comment! :-) Nevertheless, you are neither prohibited, nor are you fully -required to determine that this or the previous sentence is either false and/or -perhaps misleading. Therefore, it might be wise for you to not fail to consider -to not do so, accordingly. Thank you very much.
-
Any complaints about the above guideline could be addressed to the -Speaker of the House of Commons, or to the speaker of your national -parliament should you have one.
-We LIKE programs that:
-Some types of programs can’t excel (anti-tm) in some areas. Your -program doesn’t have to excel in all areas, but doing well in several -areas really does help.
-You are better off explaining what your submission does in your
-remarks.md file section rather than leaving it obscure for the
-IOCCC judges as we might miss something and/or be too tired to
-notice.
Please avoid this specific individual guideline, if it at all possible.
-We freely admit that interesting, creative or humorous comments in
-your remarks.md file help your chances of winning. If you had to
-read so many twisted submissions, you too would enjoy a good laugh or two.
-We think the readers of the contest winners do as well. We do read
-your remarks.md content during the judging process, so it is worth your
-while to write a remarkable remarks.md file.
We DISLIKE C code with trailing control-M’s (\r or \015) that results
-in compilation failures. Some non-UNIX/non-Linux tools such as
-MS Visual C and MS Visual C++ leave trailing control-M’s on lines.
-Users of such tools should strip off such control-M’s before submitting
-their submissions. In some cases tools have a “Save As” option that will
-prevent such trailing control-M’s being added.
One should restrict libcurses to portable features found on BSD -or Linux curses.
- -Rule 13 - Newlines -no longer discourages the use of UTF-8 -characters in C code.
-It is a very good idea to, in your remarks.md file, tell us why you
-think your submission is obfuscated. This is particularly true if
-your submission has some very subtle obfuscations that we might
-otherwise overlook. <<– Hint!
Anyone can format their code into a dense blob. A really clever -author will try format their submission using a “normal” formatting style -such that at first glance (if you squint and don’t look at the details) -the code might pass for non-obfuscated C. Deceptive comments, -and misleading formatting, in some cases, may be a plus. On the -other hand, a misleading code style requires more source bytes.
-If you do elect to use misleading formatting and comments, we
-suggest you remark on this point in your remarks.md where you talk
-about why you think your submission is obfuscated. On the other hand,
-if you are pushing up against the size limits, you may be forced
-into creating a dense blob. Such are the trade-offs that obfuscators face!
We prefer code that can run on either a 64-bit or 32-bit -processor. However, it is UNWISE to assume it will run on an -some Intel-like x86 architecture**.
-We believe that Mark Twain’s quote:
---Get your facts first, then you can distort them as you please.
-
… is a good motto for those writing code for the IOCCC.
-The IOCCC size tool source is not an original work, unless you are Anthony C -Howe, in which case it is original! :-) -Submitting source code that uses the contents of -iocccsize.c, -unless you are Anthony C Howe, might run the -risk of violating -Rule 7 - Original Work.
-The IOCCC submission tarball validator source is not an original work, -unless you are Cody Boone Ferguson, in -which case it is original! :-) Submitting source code that uses the contents of -txzchk.c, -unless you are Cody Boone Ferguson, might -run the risk of violating -Rule 7 - Original Work.
-In addition to the above tools, none of the mkiocccentry -tools, including, but not -limited to -mkiocccentry, -chksubmit, -chksubmit, -fnamchk -and -location, -nor the JSON parser and -library, -jstrencode, -jstrdecode -or any of the other jparse -tools -(see the jparse repo), are original works, -unless you are Cody Boone Ferguson or -Landon Curt Noll, in which case they -are original! :-) Submitting source code that uses the content of any of these tools or -library, unless you are Cody Boone -Ferguson or Landon Curt -Noll, might run the risk of violating -Rule 7 - Original Work.
-And unless you are Landon Curt Noll, -the code in -dbg and -dyn_array are -not original works. Submitting source code that uses the contents of those -libraries, unless you Landon Curt Noll, -might run the risk of violating -Rule 7 - Original Work.
-Rule 7 - Original Work -does not prohibit you from writing your own -obfuscated versions of these tools, unless of course you are Landon Curt -Noll, in which case you probably -won’t win since IOCCC judges should not enter the IOCCC! :-) -However, if you do write your own version, you might wish to make it do something -more interesting than simply implementing the IOCCC -tools’ algorithms.
-Even so, we do not recommend you try and submit a JSON parser due to -the fact it will likely exceed -Rule 2 - Size -and because you likely can’t beat flex and -bison in obfuscation. This isn’t to -say that the so-called JSON spec is not -obfuscated, but unless you have some really clever way to compact and -obfuscate a JSON parser more than flex and -bison you will likely not win, either -because of the -Rule 2 - Size -or because it is not -as obfuscated as the flex and bison -generated code of -jparse.
-While programs that only run in a specific word size are OK, if you have -to pick, choose a 64-bit word size.
-If the IOCCC judges are feeling ornery we -might choose to compile your program for running on an Arduino or -a PDP-11. Heck, should we ever find an emulator of 60-bit CDC Cyber -CPU, we might just try your submission on that emulator as well :-)
-If your submission MUST run only on a 64-bit or 32-bit architecture,
-then you MUST specify the -arch on your command line
-(see ARCH in the example
-Makefile, described in Makefile section). Do not assume a
-processor word size without specifying -arch. For example:
ARCH= -m64Note, however, that some platforms will not necessarily support some
-architectures. For instance, more recent versions of macOS do NOT support
-32-bit!
If there are limitations in your submission, you are highly encouraged
-to note such limitations in your remarks.md file. For example if your
-submission factors values up to a certain size, you might want to state:
--This submission factors values up
-2305567963945518424753102147331756070. -Attempting to factor larger values will produce unpredictable results.
The IOCCC judges might try to factor the value -5, so you want to might state:
---This submission factors positive values up -
-2305567963945518424753102147331756070. Attempting to factor large values will -produce unpredictable results.
However the IOCCC judges might try to also factor 0, so you want to might state:
---This submission factors values between 1 and -
-2305567963945518424753102147331756070. Attempting to factor values outside -that range will produce unpredictable results.
Moreover they might try to also factor 3.5 or 0x7, or Fred, so you want to might state:
---This submission factors integers between 1 and -
-2305567963945518424753102147331756070. Attempting to factor anything else -will produce unpredictable results.
You submission might be better off catching the attempt to factor bogus values -and doing something interesting. So you might want to code accordingly and state:
---This submission factors integers between 1 and
-2305567963945518424753102147331756070. -Attempting to factor anything else will cause the program to insult your pet fish Eric.
The IOCCC judges might not have a pet fish named Eric, so you might want to state:
---This submission factors integers between 1 and -
-2305567963945518424753102147331756070. Attempting to factor anything else -will cause the program to insult your pet fish Eric, or in the case that you -lack such a pet, will insult the pet that you do not have.
When all other things are equal, a submission with fewer limitations will be judged -better than a submission with lots of limitations. So you might want to code accordingly -and state:
---This submission attempts to a factor value of any size provided that the -program is given enough time and memory. If the value is not a proper integer, -the program might insult a fish named Eric.
-
Do not fear if you’re not 100% sure of the significance of
-2305567963945518424753102147331756070 as it is not of prime importance: or is
-it? :-)
We DISLIKE the use of ASCII tab characters in markdown files, such as in the required remarks.md file.
We don’t mind the use of ASCII tab characters in your C code. Feel free -to use ASCII tab characters if that suits your obfuscation needs. If is -perfectly OK to use tab characters elsewhere in your submission, just not in -markdown files as this tends annoy us when it comes time to -rendering your markdown content as it complicates the process.
-If you do use ASCII tab characters in your non-markdown files, be -aware that some people may use a tab stop that is different than the common 8 -character tab stop.
-PLEASE observe our IOCCC markdown guidelines
-when forming your submission’s remarks.md file. And if your submission
-contains additional markdown files, please follow those same guidelines for
-those files. See also
-Rule 4 - Files,
-and the
-FAQ on “markdown”.
We LIKE reading remarks.md files, especially if they contain
-useful, informative, and even humorous content about your submission. Yes, this
-is a hint. :-)
We RECOMMEND you put a reasonable amount effort into the content of the
-remarks.md file: it is a required file for a reason. :-)
Try to be even more creative!
-Jump to: top
-We try to avoid limiting creativity in our IOCCC rules so +we leave the contest open for creative rule interpretation.
+We do realize that there are holes in the IOCCC rules, and invite +submitters to attempt to exploit them.
+We sometime award ‘Best abuse of the rules’ or ‘Worst abuse of the rules’, +or some variation to a submission that creatively attempts to exploit a holes in the +IOCCC rules.
+When we do need to plug a hole in the IOCCC rules or +IOCCC guidelines, we will attempt to use a very small plug, +if not smaller.
+Or, maybe not. :-)
Legal abuse of the IOCCC rules is somewhat encouraged. Legal rule abuse may involve, but is not limited to, doing things that are technically allowed by the IOCCC rules and yet do not fit the spirit of what we intended to be @@ -1890,222 +632,751 @@ product management and even from customers themselves on an all too regular basi This is one of the reasons why the IOCCC rules and IOCCC guidelines are written in obfuscated form.
Jump to: top
-Submissions are judged by Leonid A. Broukhis and Landon Curt Noll.
-Each submission submitted is given a random string and subdirectory. The
-submission files including, but not limited to prog.c, Makefile,
-remarks.md, .info.json, .auth.json as well as any data files that you
-submit, are all placed under their own directory and stored and judged from this
-directory.
Any information about the authors is not read by the IOCCC judges until -the judging process is complete, and then only from entries that have -won an award. Because we do not read this information for entries that -do not win, we do not know who did not win.
-The above process helps keep us biased for/against any one particular -individual. Therefore you MUST refrain from putting any information -that reveals your identity in your submission.
-Now some people point out that coding and/or writing style might reveal the -information about the authors. However we consider this to be simply -circumstantial and outside the scope of the above paragraph.
-Some people, in the past, have attempted to obfuscate their identity by -including comments of famous Internet personalities such as Peter -Honeyman. The IOCCC judges are on to this trick -and therefore consider any obfuscated source or data file claiming to be from -Honeyman to not be from Honeyman. This of course creates an interesting paradox -known as the “obfuscated Peter Honeyman paradox”. Should Peter Honeyman -actually submit to the IOCCC, he alone is excluded from the above, as we -will likely believe it’s just another attempt at confusion. This guideline is -known as the “Peter Honeyman is exempt” guideline.
-BTW: None of the submissions claiming to be from Peter Honeyman have ever -won an award. So it is theoretically possible that Peter Honeyman -did submit to the IOCCC in the past. In the past, Peter had denied -submitting anything to the IOCCC. Perhaps those submissions were -submitted by one of his students?
-Hopefully we are VERY CLEAR on this point! The rules now strongly state:
-PLEASE DO NOT put a name of an author, in an obvious way, into your
-source code, remarks.md, data files, etc., the above “Peter Honeyman is
-exempt” notwithstanding.
We seemed to have digressed again … :-) Returning to the judging process:
-We prefer to be kept in the dark as much as you are until the final -awards are given. We enjoy the surprise of finding out in the end, -who won and where they are from.
-We attempt to keep all submissions anonymous, unless they win an award. -Because the main ‘prize’ of winning is being announced, we make all -attempts to send non-winners into oblivion. We remove all non-winning -files, and shred all related printouts. By tradition, we do not even -reveal the number of submissions that we receive.
-During the judging process, a process that spans multiple sessions over -a few weeks, we post general updates from our Mastodon -account.
-Make sure you reload the feed every so often because unless you -are mentioned you will NOT get a push notification!
+You may use git, or services such as GitHub +to develop and maintain your submission. However, we DISLIKE +submissions that require such services in order to build/compile your submission.
+Submissions will be judged in an environment that has no IDE. +Any submission that fails to compile/build because it requires +an IDE will be rejected.
+We will use the make(1) tool, your Makefile, as well as tools found in the
+Single UNIX Specification
+environments, and commonly found on systems that reasonably conform to the
+Single UNIX Specification
+in the building and compiling of your submission.
Jump to: top
-Judging consists of a number of elimination rounds. During a round, -the collection of submissions are divided into two roughly equal piles; -the pile that advances on to the next round, and the pile that does -not. We also re-examine the submissions that were eliminated in the -previous round. Thus, a submission gets at least two readings and -often more than two.
+We STRONGLY recommend you do install the +mkiocccentry toolkit +as use of using older versions of the mkiocccentry toolkit to are HIGHLY LIKELY to be REJECTED!
+If you submit your own JSON files (other than .auth.json and
+.info.json) then they do NOT have to be valid JSON.
However, if you do provide invalid JSON files, PLEASE
+document and clearly explain this in your remarks.md file.
If you use an optional filename for something other than their intended use +in order to get past the file limit, we will consider that an abuse of rules.
+Your tarball does NOT reveal who you are! For this reason, the tarball +MUST be a v7 format tarball.
+You should NOT use a tarball as an extra file for a test-suite unless you
+have a very good reason for this: if you do include a tarball as an extra file,
+then you MUST specify why in your remarks.md file.
If you DO include a tarball an extra file, and the build process or the program extracts
+said tarball(s), the make clobber rule MUST remove the extracted files.
Instead of including a large test-suite that requires a lot of files as part of your submission,
+and your submission doesn’t require the test-suite to be available to run,
+then in your remarks.md a URL where such a test-suite may be downloaded from
+and how to use the test-suite to test your submission.
See FAQ on “What should I do with the try.sh and try.alt.sh scripts?”.
See FAQ on “What is a .auth.json file?”.
See FAQ on “What is a .info.json file?”.
See FAQ on “How can I validate my submission directory?”.
+See FAQ on “What permissions may my files be and what if I need different permissions?”.
+See FAQ on “What are the detailed recommendations for a submission Makefile?”.
+See FAQ on “What are the details behind Rule 17 - Packaging?”.
Jump to: top
-A reading consists of a number of actions:
+The IOCCC submit server, and related services +use the most recent version of the +mkiocccentry toolkit: +submissions that package using older versions of the +mkiocccentry toolkit +are LIKELY to be REJECTED!
+You REALLY SHOULD use latest mkiocccentry toolkit +to package your own submission.
+The mkiocccentry(1) tool runs a number of checks by way of these
+mkiocccentry toolkit
+tools:
prog.c, the C source and reviewing the remarks.md information#included files#included filesIn later rounds, other actions are performed including performing -miscellaneous tests on the source and binary.
-This is the very guideline that goes, BING!
-Okay, technically that was the second guideline that goes BING, and this -is the third. :-)
-Until we reduce the stack of submissions down to about 25 submissions, -submissions are judged on an individual basis. A submission is set aside because it -does not, in our opinion, meet the standard established by the round. -When the number of submissions thins to about 25 submissions, we begin to form -award categories. Submissions begin to compete with each other for awards. -A submission will often compete in several categories.
-The actual award category list will vary depending on the types of submissions -we receive. A typical category list might be:
+Do NOT use txzchk(1) command line options that are labeled “for TESTING purposes”
+in the txzchk(1) man page.
Do NOT use fnamchk(1) command line options that are labeled “for TESTING purposes”
+in the fnamchk(1) man page.
Do NOT use chkentry(1) command line options that are labeled “for the use by the IOCCC judges only”
+in the chkentry(1) man page.
To view mkiocccentry toolkit man pages, +while your current directory is the top of the source tree:
+ man soup/man/man1/mkiocccentry.1
+ man soup/man/man1/iocccsize.1
+ man soup/man/man1/txzchk.1
+ man test_ioccc/man/man1/fnamchk.1
+ man soup/man/man1/chksubmit.1
+ man soup/man/man1/chkentry.1The above man(1) commands will show the toolkit man pages without having to install them first.
So that you do not have to repeatedly answer all the mkiocccentry(1) questions,
+use mkiocccentry -a answers ... to create a file containing the answers you first give,
+that will allow you to later use mkiocccentry -i answers ... to reuse those same answers.
The mkiocccentry -A answers .. does the same thing except that the answers file will be overwritten.
The mkiocccentry -i answers .. will still be required to confirm “Yes/No” questions.
Use mkiocccentry -Y -i answers .. to force a yes answers with great caution
+because it might force a yes answer to something you do NOT want.
To help with not having to repeatedly enter a UUID, put your UUID into a file and use
+mkiocccentry -u uuidfile .., or use mkiocccentry -U UUID .. to give the UUID
+on the command line.
If you wish to test that your submission passes the mkiocccentry(1) tests
+without having to type in in answers each time, you can use the -d or -s seed
+option to mkiocccentry for the tool to pseudo-randomly create answers for you.
+For example:
mkiocccentry -d workdir topdirDo NOT submit a tarball formed by mkiocccentry -d .., NOR by mkiocccentry -s seed ..!
The mkiocccentry(1) tool creates an xz(1) compressed v7 format tarball using a tar(1)
+command of the form:
cd workdir/UUID-slot_num && tar --format=v7 -cJf submit.UUID-slot_num.timestamp.txz UUID-slot_numIn many places the mkiocccentry(1) tool will prompt you to verify what you input, allowing you to
+correct details as you go along.
Pressing the “enter key” mkiocccentry(1) tool prompts will allow you to proceed with a default,
+however make sure the default is the CORRECT answer.
The mkiocccentry(1) tool will use code from iocccsize(1) which detects a number of
+issues (such as Rule 2 - Size) that you may ignore,
+however ignoring such issues comes with a significant level of risk!
Once the tarball is packaged it will
+run txzchk(1), which will also run fnamchk(1), as part of its algorithm.
The use of mkiocccentry -W ... is highly discouraged as this may ignore
+warnings about a problem that may cause your submission to be REJECTED!”
If mkiocccentry encounters an error, the program will exit and the xz
+compressed tarball will NOT be formed: this is a feature, not a bug!
If you encounter a bug with the
+mkiocccentry toolkit
+PLEASE run the bug_report.sh script to help us out here!
While you don’t have to install the
+mkiocccentry toolkit,
+then in order to run a tool outside the repo directory
+you will have to specify mkiocccentry(1) command line options to locate required tools
+such as chkentry(1) (mkiocccentry -C chkentry ..), txzchk(1) (mkiocccentry -T txzchk ..),
+and fnamchk(1) (mkiocccentry -F fnamchk ..).
The mkiocccentry(1) tool will ignore any filename that begins with a “.” (dot).
The mkiocccentry(1) tool will ignore any directory tree with a directory name that begins with a “.” (dot).
The mkiocccentry(1) tool will all files that begin with COPYING, COPYRIGHT, and LICENSE, regardless
+of filename case.
The mkiocccentry(1) tool will any of the following files if they are found directly under
+the top level directory (topdir):
[0-9][0-9][0-9][0-9]_*.tar.bz2 file globWe do not limit ourselves to this list. For example, a few submissions are so -good/bad that they are declared winners at the start of the final round. -We will invent awards categories for them, if necessary.
-In the final round process, we perform the difficult tasks of -reducing the remaining submissions (typically about 25) down to to about -half that number: declaring those remaining to be winners.
-Often we are confident that the submissions that make it into -the final round are definitely better than the ones that do not -make it. The selection of the winners out of the final round, is -less clear cut, however.
-Sometimes a final round submission is good enough to win, but is beat out by a -similar, but slightly better submission. For this reason, it is sometimes -worthwhile to resubmit an improved version of a submission that failed to win in -a previous year, the next year. This assumes, of course, that the submission is -worth improving in the first place!
-Over the years, more than one IOCCC judge -has been known to bribe another IOCCC judge into voting for a -winning submissions by offering a bit of high quality chocolate, or -other fun item.
+The files listed in the above list are allowed to exist in sub-directories: just NOT directly under
+the top level directory (topdir).
The mkiocccentry(1) tool evaluates all filenames and directory names in a case independent way:
+this FOO, Foo, and foo are treated as the SAME file even if your filesystem doesn’t.
Having two or more filenames that differ only by case WILL lead to problems because of the previous statement.
+When the mkiocccentry(1) tool ignores a file, that file is NOT included as part of your submission.
When the mkiocccentry(1) tool ignores a directory, that directory,
+and everything under that directory is NOT included as part of
+your submission.
The mkiocccentry(1) tool will ignore all symlinks.
Creating a directory directly under the top level directory (topdir)
+that is normally considered to be a regular file, such as a directory
+named Makefile, prog.alt.c, prog.c, remarks.md, try.alt.sh,
+or try.sh is NOT a good idea and will likely cause the
+mkiocccentry(1) tool to abort with a fatal error.
The required Makefile, remarks.md file may NOT be an empty file.
If the optional file try.alt.sh, or try.sh exits and is an empty file,
+the mkiocccentry(1) tool to abort with a fatal error.
If the mkiocccentry(1) tool encounters anything that isn’t a file, isn’t a directory,
+and isn’t a symlink (which the tool ignores), the mkiocccentry(1) tool to abort with a fatal error.
See FAQ on “How do I report bugs in an mkiocccentry tool?”.
See Rule 11 - Abuse for warnings about ignoring mkiocccentry(1) tool warnings.
See FAQ on “What is the fnamchk tool?”.
See FAQ on “What is mkiocccentry in simple terms?”.
+See FAQ on “What is the mkiocccentry tool, how do I obtain it and how do I use it”.
+Jump to: top
+These guideline are hints and suggestions, NOT IOCCC rules.
+While submissions that violate guideline are allowed, +submissions that remain within the IOCCC guidelines are preferred.
+You are encouraged to review the following FAQs:
+ +While the contest is open, you may modify your +previously uploaded submission by rebuilding your submission with the +mkiocccentry toolkit, +and then re-uploading it to the same slot number on the +submit server.
+The official locale of the IOCCC is C.
+You are encouraged to examine the winners of previous contests.
+Because rules change from year to year, some winning entries +of the past may be rejected this year.
+What was was unique and novel one year might be ‘old’ the next year.
+A submission is usually examined in a number of ways. We typically apply +a number of tests to a submission:
+#include lines#define and #include linesclang-format(1))You should consider how your submission looks in each of the above tests. +You should ask yourself if your submission remains obscure after it has been +‘cleaned up’ by the C pre-processor and a C beautifier.
+Your submission need not pass all of the above tests as in certain cases, +a test is not important.
+Submissions that compete for the +‘strangest/most creative source layout’ need not do as well as +others in terms of their algorithm.
+Given two submissions, we are more inclined to pick the submission that +does something interesting when it’s executed.
+IMPORTANT: Be sure that your submission works as documented in your remarks.md file.
We sometimes make an effort to debug a submission +that has a slight problem, particularly in or near the final round. +On the other hand, we have seen some otherwise excellent submissions +fall down because they didn’t work as documented.
+If you submission has bugs and/or mis-features, you are MUCH BETTER off
+documenting such bugs and/or mis-features in your remarks.md file.
Consider an example of a prime number
+printing program that claims that 16 is a prime number.
+Noting such a bug in your remarks.md file could save your submission:
++“this submission sometimes prints the 4th power of a prime by mistake”
+
Sometimes a strange bug or (mis-)feature can even help the submission! Of course, a correctly +working submission might be better.
+We tend to look down on a
+prime number
+printer that claims that 16 is a prime number.
+Clever people will note that 16 might be prime under certain conditions. ;-)
+Wise people, when submitting something clever
+will fully explain such cleverness in their submission’s remarks.md file.
People who are considering to just use some complex mathematical +function or state machine to spell out something such as “hello, +world!” really really, and we do mean REALLY, do need to be more creative.
+Consider using misleading or subtle tricks layered on top of or under +an appropriate level of obfuscation.
+A clean looking program with +misleading comments and variable names might be a VERY GOOD START +to a great submission!
+Jump to: top
+We VERY MUCH LIKE submissions that use an edited variant of the
+example Makefile, as described and linked to in the Makefile section,
+renamed as Makefile of course. This makes it easier for the IOCCC judges
+to test your submission. And if your submissions wins, it makes it easier to integrate it into
+the Official IOCCC winner website.
We VERY MUCH LIKE submissions that have some educational value. This does NOT mean
+that your submission should not be obfuscated but rather that the IOCCC has moved away from
+the idea of “spoilers”. You should not encrypt or rot13 content in your remarks.md file.
It is VERY MUCH appreciated if your remarks have some educational +value. And although educational value is not required, it is an +EXCELLENT bonus.
+We LIKE submissions that use an edited version of the
+try.sh example script (and if you have alternate code,
+the same applies with the try.alt.sh script):
Of course, it is quite possible that only one invocation is +possible, so it is not necessarily detrimental to your submission if you do not +include one, though we do like interesting and creative uses of submissions. See +also the +FAQ on “submitting try.sh and try.alt.sh scripts”.
-One should NOT attempt to bribe an IOCCC -judge, unless you are an IOCCC judge, -because bribing an IOCCC judge by a non-judge -has been shown to NOT be effective when the person attempting -the bribe is made known to the IOCCC judges -(i.e., they are not anonymous) AND/OR the bribe is otherwise -associated with a submission to the IOCCC.
-With the previous guideline in mind: anonymous gifts -for the IOCCC judges that are NOT ASSOCIATED -WITH a submission to the IOCCC may be sent to the -IOCCC judges via the -IOCCC Amazon wishlist. -It has been shown that receiving anonymous gifts provides the -IOCCC judges with a nice -dopamine boost, and happy -IOCCC judges help make the IOCCC better for everyone. :-)
-See the -FAQ on “supporting the IOCCC”.
-More often than not, we select a small submission (usually one line) and a -strange/creative layout submission. We sometimes also select a -submission that abuses the IOCCC guidelines in an interesting way, -or that stretches the contest rules that while legal, it -nevertheless goes against the intent of the rules.
-Nevertheless, see -Rule 10 - Privileges.
-In the end, we traditionally pick one submission as ‘best’. Sometimes such -a submission simply far exceeds any of the other submissions. More often, the -‘best’ is picked because it does well in a number of categories.
-In years past, we renamed the winning submission from prog.c to a
-name related to the author(s)’ names. This is no longer done.
-Winning source is called prog.c. A compiled binary is called prog.
Jump to: top
-The IOCCC judges will toot initial announcement of who won, the name -of their award, and a very brief description (award title) of the winning entry -from the @IOCCC Mastodon account.
-We recommend that you follow us on mastodon but please make sure to -refresh the feed every so often (if not more often) because unless you are -mentioned or someone boosts your post you will not get a push notification.
-Jump to: top
-The current status of the IOCCC will change from -judging to closed .
-The contest_status in the status.json file will change -from judging to closed as well.
-When the above happens, the winning entries have been selected by the IOCCC -judges.
-The IOCCC judges will begin to prepare to release the source -code of the new IOCCC winners.
-The IOCCC judges will commit the winning source to the -IOCCC winner repo which will update the -Official IOCCC website.
-The IOCCC news will also contain an announcement of the winners.
-Jump to: top
-Consider joining the IOCCC discord community via this link: -https://discord.gg/Wa42Qujwnw
+ +Doing masses of #defines to obscure the source has become ‘old’. We
+tend to ‘see thru’ masses of #defines due to our pre-processor tests
+that we apply. Simply abusing #defines or -Dfoo=bar won’t go as far
+as a program that is more well rounded in confusion.
Many C compilers DISLIKE the following code, and so do we:
+ #define d define
+ #d foo /* <-- don't expect this to turn into #define foo */In other words, it is a compilation error, and in order to get older +IOCCC winning entries that did this to compile, we had to update them to not do this.
+When declaring local or global variables, you should declare the type:
+ int this_is_fine;
+ this_is_not; /* <-- Try to avoid implicit type declarations */We tend to like less a submission that requires either
+gcc OR clang. We prefer submissions that can compile
+under BOTH gcc AND clang. Hint!
We RECOMMEND that the compiler flags you use in your
+submission’s Makefile are supported by BOTH gcc AND clang.
We DISLIKE the use of obscure compiler flags, especially
+if gcc and/or clang do not support it. We suggest
+that you not use any really obscure compiler flags if you can help it.
One side effect of the above is that you cannot assume the use +of nested functions such as:
+ int main() {
+| void please_dont_submit_this() {
+| printf("The machine that goes BING!!\n");
+ }
+| please_dont_submit_this();
+ }On 2012 July 20, the IOCCC judges rescinded the encouragement of
+nested functions. Such constructions, while interesting and sometimes
+amusing, will have to wait until they are required by a C standard that are
+actually implemented in BOTH gcc AND clang.
We DISLIKE submissions that require the use of -fnested-functions.
If your submission uses functions that have a variable number of
+arguments, be careful. Systems implement va_list in a wide variety
+of ways. Because of this, a number of operations using va_list are
+not portable and must not be used:
va_list variable to/from a va_list variableva_list variable into/from a va_list variableva_list variable to a function expecting a non-va_list argva_list variable to a function expecting a va_list argva_list variablesva_list as a structure or unionIn particular, do not treat va_list variables as if they were a char **.
We DISLIKE the use of varargs.h. Use stdarg.h instead.
We DISLIKE the use of gets(3). Use fgets(3) instead.
We tend to DISLIKE the blatant use of tarballs in an attempt to simply get
+around the extra file number limit. We realize there may be cases where a
+tarball containing a number of extra files may be needed. Such a need for a
+tarball MUST be explained in the remarks.md file.
On 28 January 2007, the Judges rescinded the requirement that the
+# in a C preprocessor directive must be the 1st non-whitespace byte.
The exit(3) function returns void. Some broken systems have exit(3)
+return int; your submission should assume that exit(3) returns a void.
Small programs are best when they are short, obscure and concise. +While such programs are not as complex as other winners, they do +serve a useful purpose: they are often the only program that people +attempt to completely understand. For this reason, we look for +programs that are compact, and are instructional.
+One line programs should be short one line programs: say around 80 to 132 +bytes long. Going well beyond 132 bytes is a bit too long to be called +a one-liner in our vague opinion.
+We tend to DISLIKE programs that:
+index(3)/strchr(3) differences are OK, but
+sockets/streams specific code is likely not to be)remarks.md file)In order to encourage submission portability, we DISLIKE submissions that +fail to build unless one is using an IDE. For example, do not +mandate that one must use Microsoft Visual Studio to compile +your submission.
+The program must compile and link cleanly in a Single UNIX +Specification +environment. Therefore do not assume the system has a +windows.h include file:
+ #include <windows.h> /* we DISLIKE this */Unless you are cramped for space, or unless you are entering the +‘Best one liner’ category, we suggest that you format your program +in a more creative way than simply forming excessively long lines.
+The Makefile should not be used to try and get around the size limit. It is
+one thing to make use of a several -Ds on the compile line to help out, but it
+is quite another to use many bytes of -Ds in order to try and squeeze the
+source under the size limit.
Your source code, post-pre-processing, should not exceed the size of +Microsoft Windows. :-)
+You should try to restrict commands used in the build file to commands found in +Single UNIX +Specification +environments and systems that conform to the Single UNIX +Specification.
+You may compile and use your own programs. If you do, try to build and execute +from the current directory. This restriction is not a hard and +absolute one. The intent is to ensure that the building of your +program is reasonably portable.
+We prefer programs that are portable across a wide variety of UNIX-like +operating systems (e.g., Linux, GNU Hurd, BSD, UNIX, etc.).
+Don’t forget that the building of your program should be done +WITHOUT human intervention. So don’t do things such as:
+ prog: prog.c
+ #echo this next line requires data from standard input
+ cat > prog.c
+ ${CC} prog.c -o progHowever, you can do something cute such as making your program
+do something dumb (or cute) when it is built ‘automatically’, and
+when it is run with a human involved, do something more clever.
+For example, one could put in their Makefile:
prog: prog.c
+ ${CC} prog.c -DNON_HUMAN_COMPILE -o prog
+ @echo "See remarks section about alternate ways to compile"and then include special notes in your remarks.md file for
+alternate / human intervention based building.
We want to get away from source that is simply a compact blob of +bytes. REALLY TRY to be more creative than blob coding. HINT!
+Please do not use things like gzip(1) to get around the size limit.
+Please try to be much more creative.
We really DISLIKE submissions that make blatant use of including +large data files to get around the source code size limit.
+Did we remember to indicate that programs that blatantly use +some complex state machine to do something simple, are boring? +We think we did. :-)
+Given two versions of the same program, one that is a compact blob +of code, and the other that is formatted more like a typical C +program, we tend to favor the second version. Of course, a third +version of the same program that is formatted in an interesting +and/or obfuscated way, would definitely win over the first two! +Remember, you can submit more than one submission. See the +IOCCC rules +for details (in particular, +Rule 8 - Submission).
+We suggest that you avoid trying for the ‘smallest self-replicating’ +source. The smallest, a zero byte entry, won in +1994.
+Programs that claim to be the smallest C source that does something, really +better be the smallest such program or they risk being rejected because +they do not work as documented.
+Please note that the C source below, besides lacking in obfuscation, +is NOT the smallest C source file that when compiled and run, dumps core:
+ main;Unless you specify -fwritable-strings (see COTHER in the example
+Makefile, described in the Makefile section), do not assume this
+sort of code will work:
char *T = "So many primes, so little time!";
+ ...
+ T[14] = ';'; /* modifying a string requires: -fwritable-strings */Even so, one should probably not assume that this is universally accepted.
+Initialized char arrays are OK to write over. For instance, this is OK:
+ char b[] = "Is this OK";
+ b[9] = 'k'; /* modifying an initialized char array is OK */X client submissions should be as portable as possible. Submissions that +adapt to a wide collection of environments will be favored. For +example, don’t depend on a particular type or size of display. +Don’t assume the use of a particular browser. Instead assume a +generic browser that forms to a widely used W3C +standard. +Don’t assume a particular sound sub-system or video driver is installed +in the OS. Instead, make use of a well known and widely available open +source program (one that actually works) to display audio/visual data.
+X client submissions should avoid using X related libraries and +software that are not in wide spread use.
+As of Red Hat RHEL9.0, the X.org server is deprecated. See the +FAQ on “Xorg deprecation”” +for more details. This does not mean that a submission using this will +necessarily be rejected, but it would be better if it can support Wayland in +some way or another.
+We DISLIKE submissions that use proprietary toolkits such as the M*tif,
+Xv*ew, or OpenL*ok toolkits, since not everyone has them. Use an
+open source toolkit that is widely and freely available instead.
X client submissions should try to not to depend on particular items in
+.Xdefaults. If you must do so, be sure to note the required lines
+in the your remarks.md file. They should also not depend on any
+particular window manager.
Try to avoid submissions that play music that some people believe is copyrighted +music.
+While we recognize that UNIX is not a universal operating system, the contest +does have a bias towards such systems. In an effort to expand the scope of the +contest, we phrase our bias to favor the Single UNIX +Specification.
+You are well advised to submit code that conforms to the Single UNIX +Specification Version 4.
+To quote the IOCCC judges:
+We LIKE programs that:
+Some types of programs can’t excel (anti-tm) in some areas. Your +program doesn’t have to excel in all areas, but doing well in several +areas really does help.
+You are better off explaining what your submission does in your
+remarks.md file section rather than leaving it obscure for the
+IOCCC judges as we might miss something and/or be too tired to
+notice.
We freely admit that interesting, creative or humorous comments in
+your remarks.md file help your chances of winning. If you had to
+read so many twisted submissions, you too would enjoy a good laugh or two.
+We think the readers of the contest winners do as well. We do read
+your remarks.md content during the judging process, so it is worth your
+while to write a remarkable remarks.md file.
We DISLIKE C code with trailing control-M’s (\r or \015) that results
+in compilation failures. Some non-UNIX/non-Linux tools such as
+MS Visual C and MS Visual C++ leave trailing control-M’s on lines.
+Users of such tools should strip off such control-M’s before submitting
+their submissions. In some cases tools have a “Save As” option that will
+prevent such trailing control-M’s being added.
One should restrict libcurses to portable features found on BSD +or Linux curses.
+ +Rule 13 - Newlines +no longer discourages the use of UTF-8 +characters in C code.
+It is a very good idea to, in your remarks.md file, tell us why you
+think your submission is obfuscated. This is particularly true if
+your submission has some very subtle obfuscations that we might
+otherwise overlook. <<– Hint!
Anyone can format their code into a dense blob. A really clever +author will try format their submission using a “normal” formatting style +such that at first glance (if you squint and don’t look at the details) +the code might pass for non-obfuscated C. Deceptive comments, +and misleading formatting, in some cases, may be a plus. On the +other hand, a misleading code style requires more source bytes.
+If you do elect to use misleading formatting and comments, we
+suggest you remark on this point in your remarks.md where you talk
+about why you think your submission is obfuscated. On the other hand,
+if you are pushing up against the size limits, you may be forced
+into creating a dense blob. Such are the trade-offs that obfuscators face!
We prefer code that can run on either a 64-bit or 32-bit +processor. However, it is UNWISE to assume it will run on an +some Intel-like x86 architecture**.
+While programs that only run in a specific word size are OK, if you have +to pick, choose a 64-bit word size.
+If your submission MUST run only on a 64-bit or 32-bit architecture,
+then you MUST specify the -arch on your command line
+(see ARCH in the example
+Makefile, described in Makefile section). Do not assume a
+processor word size without specifying -arch. For example:
ARCH= -m64Note, however, that some platforms will not necessarily support some
+architectures. For instance, more recent versions of macOS do NOT support
+32-bit!
If there are limitations in your submission, you are highly encouraged
+to note such limitations in your remarks.md file. For example if your
+submission factors values up to a certain size, you might want to state:
++This submission factors values up
+2305567963945518424753102147331756070. +Attempting to factor larger values will produce unpredictable results.
The IOCCC judges might try to factor the value -5, so you want to might state:
+++This submission factors positive values up +
+2305567963945518424753102147331756070. Attempting to factor large values will +produce unpredictable results.
However the IOCCC judges might try to also factor 0, so you want to might state:
+++This submission factors values between 1 and +
+2305567963945518424753102147331756070. Attempting to factor values outside +that range will produce unpredictable results.
Moreover they might try to also factor 3.5 or 0x7, or Fred, so you want to might state:
+++This submission factors integers between 1 and +
+2305567963945518424753102147331756070. Attempting to factor anything else +will produce unpredictable results.
You submission might be better off catching the attempt to factor bogus values +and doing something interesting. So you might want to code accordingly and state:
+++This submission factors integers between 1 and
+2305567963945518424753102147331756070. +Attempting to factor anything else will cause the program to insult your pet fish Eric.
The IOCCC judges might not have a pet fish named Eric, so you might want to state:
+++This submission factors integers between 1 and +
+2305567963945518424753102147331756070. Attempting to factor anything else +will cause the program to insult your pet fish Eric, or in the case that you +lack such a pet, will insult the pet that you do not have.
When all other things are equal, a submission with fewer limitations will be judged +better than a submission with lots of limitations. So you might want to code accordingly +and state:
+++This submission attempts to a factor value of any size provided that the +program is given enough time and memory. If the value is not a proper integer, +the program might insult a fish named Eric.
+
We DISLIKE the use of ASCII tab characters in markdown files, such as in the required remarks.md file.
We don’t mind the use of ASCII tab characters in your C code. Feel free +to use ASCII tab characters if that suits your obfuscation needs. If is +perfectly OK to use tab characters elsewhere in your submission, just not in +markdown files as this tends annoy us when it comes time to +rendering your markdown content as it complicates the process.
+If you do use ASCII tab characters in your non-markdown files, be +aware that some people may use a tab stop that is different than the common 8 +character tab stop.
+PLEASE observe our IOCCC markdown guidelines
+when forming your submission’s remarks.md file. And if your submission
+contains additional markdown files, please follow those same guidelines for
+those files. See also
+Rule 4 - Files,
+and the
+FAQ on “markdown”.
We LIKE reading remarks.md files, especially if they contain
+useful, informative, and even humorous content about your submission. Yes, this
+is a hint. :-)
We RECOMMEND you put a reasonable amount effort into the content of the
+remarks.md file: it is a required file for a reason. :-)
Try to be even more creative!
Jump to: top
-It is pointless to ask the IOCCC judges how many -submissions we receive. See How many submissions do the judges receive for a -given IOCCC?.
-Often, winning entries are published in selected magazines from around the
-world. Winners have appeared in books (‘The New Hacker's Dictionary’,
-‘Obfuscated C and Other Mysteries’, ‘Pointers On C’, others) and on t-shirts
-(sometimes by the author(s) themselves). There have been multiple classes
-that have focused in part, on IOCCC winning entries. And more than one winner has been turned
-into a tattoo!
Last, but not least, winners receive international fame and flames! :-)
+The reason for the times of day are so that key IOCCC events are calculated +to be a functional UTC time. :-)
+At least 2 of several reasons for selecting the prime, 2503, for +Rule 2b - Net Size +may be found on the “Curios!” about 2503.
+The 2503 value for Rule 2b - Net is a decimal anagram +of the number of the kernel disk pack of one of the judge’s BESM-6.
+There may or may not be fewer than 2^7+1 reasons why these IOCCC +guidelines seem obfuscated.
+Excessively “dotty” use of the chksubmit(1) or chkentry(1) commands suggests that
+either like silly things, or that you”RTFS” with some level of care.
Some people might question what actually constitutes a valid JSON file, given +the state of the “so-called” JSON spec.. :-)
+We prefer programs that do not require a fish license: crayons and +cat detector vans not withstanding.
+ +While those who are used to temperatures found on dwarf +planets +(yes Virginia, dwarf planets ARE planets!), such as +Pluto, might be able to +explain to the Walrus why our seas are boiling hot, the question of +whether pigs have wings is likely to remain a debatable point to most.
+At least one judge prefers to maintain the use of the +leap-second +as part of the world’s time standard. If your code prints time +with seconds, we prefer that your code be capable of printing the +time of day during a leap-second where the value in seconds +after the minute mark is 60.
+Other windows, on the other hand, might be OK: especially where “X +marks the spot”. Yet on the third hand, windows are best when they are +“unseen” (i.e., not dirty). :-)
+The IOCCC judges, as a group, have a history giving wide degree of latitude +to reasonable submissions. And recently they have had as much longitudinal +variation as it is possible to have on Earth. :-) +Other windows, on the other hand, might be OK: especially where “X +marks the spot”. Yet on the third hand, windows are best when they are +“unseen” (i.e., not dirty). :-)
+The IOCCC judges, as a group, have a history giving wide degree of latitude +to reasonable submissions. And recently they have had as much longitudinal +variation as it is possible to have on Earth. :-)
+++You are in a maze of twisty guidelines, all different.
+
There are at least zero IOCCC judges who think that +Fideism has little +or nothing to do with the IOCCC judging process.
+++ +All generalizations are false, including this one. – Mark Twain
+
This could be the only guideline that contains the word +fizzbin.
+However, do you know how to play fizzbin? +You do?!? (Except on Tuesday?)
+OK, there are actually 2 guidelines that contain the word +fizzbin, +unless you count this one, in which case there are 3. :-)
+NOTE: The previous guideline in this spot has been replaced by this guideline:
+++ +You very well might not be completely prohibited from failing to not partly +misunderstand this particular guideline, but of course, we could not possibly +comment! :-) Nevertheless, you are neither prohibited, nor are you fully or partly +required to determine that this or the previous sentence is either false and/or +perhaps misleading. Therefore, it might be wise for you to not fail to consider +to not do so, accordingly. Thank you very much (allegedly).
+
Any complaints about the above guideline could be addressed to the +Speaker of the House of Commons, or to the speaker of your national +parliament should you have one.
+ +We believe that Mark Twain’s quote:
+++Get your facts first, then you can distort them as you please.
+
… is a good motto for those writing code for the IOCCC.
+ + +If the IOCCC judges are feeling ornery we +might choose to compile your program for running on an Arduino or +a PDP-11. Heck, should we ever find an emulator of 60-bit CDC Cyber +CPU, we might just try your submission on that emulator as well :-)
+Do not fear if you’re not 100% sure of the significance of
+2305567963945518424753102147331756070 as it is not of prime importance: or is
+it? :-)
Jump to: top
These IOCCC Rules are version 29.05 2025-11-21.
+These IOCCC Rules are version 29.08 2025-11-28.
Be sure to read the IOCCC guidelines.
This IOCCC runs from ${START_DATE_TIME} UTC to ${CLOSE_DATE_TIME} UTC.
-This contest will enter the open state on ${OPEN_DATE_TIME} UTC.
-This contest will enter the judging state on ${JUDGMENT_DATE_TIME} UTC.
-The above dates are subject to change until the contest is officially open.
-NOTE: As of this draft, the above dates are TBD (to be determined).
+This IOCCC runs from 2025-12-03 20:25:12.045045 UTC to 2026-03-13 17:19:23.293137 UTC.
+This contest will enter the pending state on 2025-12-03 20:25:12.045045 UTC, +allowing people to register for the IOCCC.
+This contest will enter the open state on 2025-12-15 18:21:24.273033 UTC, +allowing people to upload submissions to the IOCCC submit server.
+This contest will enter the judging state on 2026-03-13 17:19:23.293137 UTC, +when people will no longer be allowed to upload submissions.
+Until the contest enters the open state, any or all +of the above dates and times may change AT ANY TIME!
+The above timestamps are in “YYYY-MM-DD HH:MM:SS.micros UTC” format.
+See Current status of the IOCCC.
iocccsize(1):
iocccsize prog.c
+See Guidelines for Rule 2 - Size.
The overall maximum size of your prog.c program source MUST NOT
exceed 4993 bytes.
See Entering the IOCCC: the bare minimum you need to know.
See Entering the IOCCC: the bare minimum you need to know.
See Rule 8 - Submission.
+See Guidelines for Rule 3 - Register.
The remarks.md and Makefile are explained in more detail in the Guidelines.
See IOCCC markdown guidelines.
See Rule 17 - Packaging.
+See FAQ on “What permissions may my files be and what if I need different permissions?”.
+See Guidelines for the mkiocccentry toolkit.
+See Guidelines for the Makefile.
In short: You wrote it, you own it, and its an original work.
You, the author(s), MUST own the contents of your submission, or you MUST
have permission from the original owner(s) to its use. If you submit
any content that is owned by others, you MUST detail that ownership,
i.e., who owns what, and document the permission you obtained from them
in your remarks.md file.
The IOCCC has a rich history of remarkable winning entries created by
-authors who skilfully employed various techniques to develop their code.
-While it isn’t required, you are allowed to use tools to develop and
-test your submission. These tools may include, but aren’t limited to
-code generators, code analysis tools, static code analysis tools, runtime
-analysis tools, machine learning tools, natural language models, code
-copilot tools, so-called AI services, large language models (LLMs), etc.
-If you do make use of such tools or services, then we encourage you to
-describe what tools and how you used those tools, in your remarks.md file.
You are permitted to use tools to write your code.
See Rule 16 - Anonymous.
+See Guidelines for Rule 7 - Original Work.
bash, gmake, gcc, clang, under a
SUS environment.
-Note references to gmake can be any GNU Make compatible tool.
NOTE: The references to gmake(1) can be any GNU Make compatible tool.
See Rule 15 - Building.
Programs that require special privileges (setuid(2), setgid(2), +
Programs that require special privileges (setuid(2), setgid(2),
super-user, special owner, special group, etc.) are HIGHLY DISCOURAGED.
We do NOT guarantee these functions will behave as you expect on our
test platforms. If your program needs special permissions you MUST
@@ -679,6 +683,7 @@ is rejected.
remarks.md file of your non-rule
abusing version so that the Judges don’t think you uploaded a duplicate
into a wrong slot by mistake.
+See Guidelines for Rule 11 - Abuse.
--example or extensions like grep -P.
Do NOT assume that . (current directory) is in the $PATH environment variable.
See Rule 4 - Files.
+See FAQ on “What are the detailed recommendations for a submission Makefile?”.
+See Guidelines for Rule 15 - Building.
prog.c, remarks.md, Makefile, prog.alt.c, try.sh, try.alt.sh,
.info.json and .auth.json is 31. And the maximum file-path
component is 38 and maximum path length is 60.
-The submission MUST be a .txz compressed tarball as constructed by
-mkiocccentry(1), which MUST be within [1..3999971] bytes in size.
-The sum of all file lengths, after unpacking from the tarball, MUST be
-less than 27651*1024 bytes.
The tarball file MUST pass all txzchk(1) checks and the tarball
-filename MUST pass all fnamchk(1) checks. You may NOT submit a tarball
-created by the -d or -s seed options of mkiocccentry(1).
The submission MUST be a .txz compressed tarball (i.e., tarball compressed by xz(1))
+as constructed by mkiocccentry(1), which MUST be within [1..3999971] bytes in size.
The tarball MUST be a v7 format tarball.
+The sum of all file lengths, after unpacking from the tarball, MUST be
+less than 27651*1024 (28314624) bytes.
The submission MUST be a tarball file that MUST pass all txzchk(1) checks, and the tarball
+filename MUST pass all fnamchk(1) checks.
You may NOT submit a tarball created by the -d, -e, NOR by the -s seed options of mkiocccentry(1).
The unpacked submission directory MUST pass the checks performed by the
current version of chksubmit(1).
Submissions may NOT use a +mkiocccentry toolkit +command line options that labeled as “for TESTING purposes”, +NOR labeled as “for the use by the IOCCC judges only”, +in their respective man pages.
+Submissions may ONLY use
+mkiocccentry toolkit
+command lines that confirm to the command’s -h “print help message”.
The prog.c file MUST pass the Rule 2 - Size
size checks performed by iocccsize(1).
The .auth.json and .info.json files MUST be compatible with what
-mkiocccentry(1) generates.
Submissions that package using older versions of the mkiocccentry -toolkit to are HIGHLY LIKELY to be REJECTED! Be sure -that you are using the latest tools from the +
The .auth.json and .info.json files MUST be compatible with what chksubmit(1) generates.
Any submission that fails to pass the checks performed by the most recent version of the mkiocccentry toolkit -GitHub repo.
-In summary: it is best to use mkioccentry(1) to package your submission,
-rather than roll-it-by-hand.
See Rule 4 - Files.
+See FAQ on “What is the mkiocccentry tool, how do I obtain it and how do I use it?”.
+See Guidelines for Rule 17 - Packaging.
See Rule 6 - Free.
Please read the Guidelines next for further commentary on these rules.
Read the Entering the IOCCC: the bare minimum you need to know for an overview of how to enter the contest.
-Please read the Guidelines next for further commentary on The Rules.
See also the FAQ.
+And now for something completely different
Consider joining the IOCCC Discord Server
for discussions about The Rules, questions for the Judges, and C in general.
Leonid A. Broukhis
+
Leonid A. Broukhis chongo (Landon Curt Noll) /\cc/\
diff --git a/next/rules.md b/next/rules.md index df55cda95..4ed0bc1eb 100644 --- a/next/rules.md +++ b/next/rules.md @@ -39,7 +39,7 @@ writing by [contacting the judges](../contact.html). ## Rules Version -These IOCCC Rules are version **29.05 2025-11-21**. +These IOCCC Rules are version **29.08 2025-11-28**. Be sure to read the [IOCCC guidelines](guidelines.html). @@ -48,15 +48,23 @@ Be sure to read the [IOCCC guidelines](guidelines.html). ## Rule 0 - Dates