Round N+1 was a marathon judging round for IOCCC29, and we made some really important progress! We’re not quite ready to dive into the final rounds of judging, but we’re getting there.

IOCCC Judges overall remark: We’re thoroughly enjoying reviewing the IOCCC29 submissions!

#ioccc #ioccc29

We’ll carefully review each submission, giving the C code and remarks.md
the time and attention they deserve.

Winners will be announced live on the "Our Favorite Universe".

https://www.youtube.com/@OurFavoriteUniverse

PLEASE subscribe to that YouTube channel and click the notification bell.
The winning source will be uploaded to www.ioccc.org at the end of the show.

We may also post progress updates on Mastodon:

https://fosstodon.org/@ioccc

And Discord server. To join:

https://discord.com/invite/Wa42Qujwnw

#ioccc #ioccc29

Our Favorite Universe

Welcome to Our Favorite Universe, where we will explore Our Favorite Universe from the perspective of Science and Math.

YouTube

The IOCCC is now closed for new submissions.

For the many who submitted to this IOCCC, we THANK YOU. Without your
efforts, talent, creativity, and C coding skill, there wouldn't be an IOCCC!

If you missed this IOCCC, please submit to the next IOCCC, which we
are happy to announce we are planning to hold another IOCCC next year.

The IOCCC judges will go into "radio silence" as we judge the many
submissions. How long depends on the submission quantity & quality.

#ioccc #ioccc29

🌗 GitHub - carlini/printf-tac-toe:僅靠單次 printf 呼叫實現的井字遊戲
➤ 當格式化輸出成為一種圖靈完備的程式語言
https://github.com/carlini/printf-tac-toe
本項目展示了一個極致的 C 語言程式設計技巧:如何僅通過單一的 `printf` 函式呼叫來實現完整的井字遊戲邏輯。作者利用 `printf` 格式化字串中不為人知的特性(特別是 `%n` 與位置參數指定符),將記憶體操作與邏輯運算轉化為字串處理,不僅實現了圖靈完備的計算模型,還編寫了一個可互動的遊戲。這項作品曾入選 IOCCC(國際 C 語言混淆程式碼大賽),是研究底層記憶體操作與編譯器行為的經典案例。
+ 這簡直是瘋狂的藝術!我從未想過 `%n` 可以被這樣濫用,這已經超越了代碼,簡直是字串上的數位邏輯電路。
+ 這是計算機科學領域的奇蹟。雖然實用性為零,但作者對 `printf` 參數處理與記憶體位址存取的洞察力令人嘆為觀止,這確實是駭客精神的巔峯。
#C 語言 #IOCCC #代碼混淆 #printf 導向編程
GitHub - carlini/printf-tac-toe: tic-tac-toe in a single call to printf

tic-tac-toe in a single call to printf. Contribute to carlini/printf-tac-toe development by creating an account on GitHub.

GitHub

The 29th International Obfuscated C Contest closes at 2026-03-13 17:19:23.293137 UTC.

You have less than a week to upload your submissions to the International Obfuscated C Code Contest!

For details see this free Patreon post:

https://www.patreon.com/posts/ioccc29-closes-152429675

#ioccc #IOCCC29

Just a friendly reminder that **IOCCC29** will be open for only 2 weeks more. The submission deadline is **2026-03-13 17:19:23.293137 UTC**.

#ioccc #ioccc29

@sirwumpus best wishes Anthony!

But on the plus side you will have more time for the #ioccc!

That’s what I have done on my free time (not that you or @ioccc would be surprised there).

Well that and had my birthday with the obviously obligatory cake. Also had home made potato soup.

Anyway good luck with the issue!

The IOCCC29 is open for less than a month (2026-03-13 17:19:23.293137 UTC).

How register: https://www.ioccc.org/next/register.html

On receipt of IOCCC email, login and change your initial password: https://www.ioccc.org/next/pw-change.html

Re-register if you didn't change your initial password in 14 days.

Obtain the mkiocccentry toolkit: https://www.ioccc.org/faq.html#obtaining_mkiocccentry

Use the mkiocccentry to form your submission compressed tarball: https://www.ioccc.org/faq.html#using_mkiocccentry

Upload your submission: https://www.ioccc.org/next/submit.html

#ioccc #ioccc29

The International Obfuscated C Code Contest

How to register for the IOCCC

Happy 2026!

IOCCC29 is open for registrations. After you have registered, you have 14 days to then log in to the submit server and change your password. If you fail to log in within 14 days, your submit server will expire and you will need to re-register.

See: https://www.ioccc.org/quick-start.html#enter

For those who have registered, you may upload your submissions. Be sure you are using your latest version of the mkiocccentry toolkit:

https://www.ioccc.org/faq.html#obtaining_mkiocccentry

#ioccc #IOCCC29

The International Obfuscated C Code Contest

IOCCC FAQ

The International Obfuscated C Code Contest (IOCCC29) is in "pending state," meaning the contest is open for you to register:

https://www.ioccc.org/next/register.html

Feel free to register today, even if you are not sure if you want to enter, instead of waiting until the last minute near the contest deadline.

On 2025 December 14th at 23:00 UTC, there will be an IOCCC Discord hangout to discuss IOCCC29. To join the IOCCC Discord server:

https://discord.gg/Wa42Qujwnw

#ioccc #ioccc29 #ioccc2025

The International Obfuscated C Code Contest

How to register for the IOCCC