The International Obfuscated C Code Contest, or IOCCC, is a programming competition for writing the most obscure and intentionally confusing C program that still compiles and works. It has run since 1984, which the contest’s own records list as “the 1st IOCCC,” making it one of the longest-running events in programming culture. The judges hold the copyright on the contest material under the name of Landon Curt Noll, one of the founders.
The contest’s own About page lists its goals plainly: “To write the most Obscure/Obfuscated C program within the rules,” “To show the importance of programming style, in an ironic way,” “To stress C compilers with unusual code,” “To illustrate some of the subtleties of the C language,” and “To have fun with C!” The irony is the point. By rewarding deliberately awful-looking code that nevertheless behaves perfectly, the contest teaches what readable code is by showing its opposite.
Entries are bound by strict size rules, which forces entrants to pack as much trickery as possible into a small space. The result is often source code laid out as ASCII art, shaped like a picture or a word, where the visual form has nothing to do with the program’s behavior. A famous example is the very first Grand Prize winner in 1984, an entry by Mullender that embedded hardcoded VAX and PDP-11 machine code to move a smiley face across the screen, exploiting machine-specific behavior in ways no normal program would.
Over the decades IOCCC winners have produced flight simulators, ray tracers, and working interpreters hidden inside source that looks like abstract patterns. The contest sits at the intersection of obfuscated code as an art form and the broader hacker culture’s delight in pushing a tool far past its intended use. It is closely related in spirit to code golf, where the goal is the fewest characters rather than the most baffling layout, and both reward an intimate, almost playful mastery of a language’s darkest corners.