International Obfuscated C Code Contest

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The International Obfuscated C Code Contest (abbreviated IOCCC) was a programming contest for the most creatively obfuscated C code, held annually between 1984 and 2006 with the exception of 1997, 1999, 2002, 2003 and 2005.[1] The winners of the 19th and final contest, held in 2006, were announced in November 2007, however, as of early 2010, the winning code has yet to be posted.[2]

Entries were submitted online, and would proceed through a number of rounds of being judged by a panel of judges. Entries were judged on how obfuscated they were, and how creatively. Entries that made it through the final round were awarded with a category, such as "Worst Abuse of the C preprocessor" or "Most Erratic Behavior", and were then announced on the official IOCCC website. Entries that did not make it were deleted and forgotten; the contest states that being announced on the IOCCC website is the award for winning.



The IOCCC was started by Landon Curt Noll and Larry Bassel in 1984 while employed at National Semiconductor's Genix porting group. The idea for the contest came after they compared notes with each other about some poorly-written code that they had to fix.[3]


Each year, the rules of the contest were published on the IOCCC website. Rules varied from year to year, and were posted with a set of guidelines that attempted to convey the spirit of the rules.

The rules were often deliberately written with subtle loopholes that contestants were somewhat encouraged to find and abuse. This was a result of the contest being a "parody of the software development process". Entries that took advantage of some loophole in the rules (whether or not they passed the final round of judging) would cause the rules for the following year's contest to be adjusted accordingly (although often other subtle loopholes were deliberately introduced in the process).

Obfuscations employed

Due to the nature of the contest, entries often employed strange or unusual tricks, such as using the C preprocessor to do things it was not designed to do, or avoiding commonly-used constructs in the C programming language in favor of much more obscure ways of achieving the same thing. For example, some quotes from 2004 winners include:

To keep things simple, I have avoided the C preprocessor and tricky statements such as "if", "for", "do", "while", "switch", and "goto".[4]

We still aren't sure whether or not this is a useful program, but it's the first atomic fission we've seen in the IOCCC.[5]

Why not use the program to hide another program in the program? It must have seemed reasonable at the time.[6]

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