the IOCCC
loreprogrammingops culture
Stands for: International Obfuscated C Code Contest
The contest, running since 1984, that celebrates the most gloriously unreadable working C programs on Earth.
Founded by Landon Curt Noll and Larry Bassel, the International Obfuscated C Code Contest rewards programs that abuse the language's every dark corner while still compiling and doing something wonderful: flight simulators shaped like airplanes, self-reproducing haiku, compilers in a few tortured lines. It is simultaneously a joke, a museum of C's semantics, and a security education, since obfuscated-but-functional is exactly what malicious code looks like. The judges' favorite category of all: abuse of the rules.
The International Obfuscated C Code Contest, running since 1984, invites entrants to write the most incomprehensible working C program they can. Winners have included programs shaped like the thing they compute, code that runs identically forwards and backwards, and entries whose behaviour is genuinely difficult to believe.
The contest is a joke with a serious function. Its entries systematically exploit the parts of C that are ambiguous, implementation-defined or merely surprising, which makes the winning programs a practical catalogue of exactly the constructs a language standard failed to pin down. Compiler authors have used them as test cases, because a program that abuses the specification is a good probe of whether an implementation follows it.
The educational value is the inverse of its appearance. Understanding why an entry works requires knowing the language considerably better than writing normal code does, and the contest demonstrates by exhibition that syntactic validity and comprehensibility are unrelated properties. It is also the most entertaining possible argument for style guides, since every entry is a legal program that no team would ever accept.