IOCCC 2026: The International Obfuscated C Code Contest

Slashdot: The Coding and Designing Club is thrilled to invite you to participate in the 29th International Obfuscated C Code Contest (IOCCC29)—the world's most creative and puzzling C programming competition running since 1984!

This is your chance to represent IISER Kolkata on a global stage and prove that you can write C code that's both brilliant and baffling.

The Challenge

Write a C program that does something useful or interesting—but make it as obfuscated as possible while still compiling and running correctly. The most creative, surprising, and clever entries win.

Contest Rules:

• Rule #1: It Must Compile. Your code must compile and run without errors using a standard C compiler (gcc, clang, etc.).
• Rule #2: Size Limit. Source code must be ≤ 4096 bytes. Comments and whitespace count toward the limit.
• Rule #3: No External Dependencies. Programs must be self-contained. No linking against unusual libraries or requiring special hardware.
• Rule #4: It Must Do Something. No empty or trivial programs. It should have a non-obvious purpose that's revealed when run.

Critical Deadline

• Final Deadline: March 13, 2026 @ 17:19:23 UTC (22:49 IST)
• Late submissions will not be accepted.

How to Register

Registration is free and required before you can submit.

1. Visit the IOCCC29 registration page and subscribe with your email.
2. Open the subscription consent email and click the confirmation URL.
3. Confirm your email and agree to the mailing list policies.
4. Read the welcome email to complete your registration and receive your submit server credentials.

"The IOCCC proves that C code can be both functional and incomprehensible — and that's a beautiful thing." — The IOCCC Judges

Classic Obfuscation Example

main(_){_^448&&main(-~_);putchar(--_%64?32|-~7[__TIME__-_/8%8][">'txiZ^(~z?"-48]>>";;;====~$::199"[_*2&8|_/64]/(_&2?1:8)%8&1:10);}