ioccc korn 87 explained

in the 1987 international obfuscated C contest, David Korn won the award "best one-liner" for the following one-liner C program:

main() { printf(&unix["\021%six\012\0"],(unix)["have"]+"fun"-0x60);}

on unix systems, it prints out "unix."

here's how it works:

if you're running a unix-based (unix-like, or whatever -- let's not be pedantic for once, shall we?) system, the symbol "unix" evaluates to "1" (aka true).
both occurrences of this symbol are examples of reverse indexing, because arr[idx] is equivalent to idx[arr] in C -- so basically, unix["\021%six\012\0"] and (unix)["have"] get the second char of the string.
the & in &unix["\021%six\012\0"] makes it a char*, basically cropping off the \021 but keeping the rest of the string.
\0 is an escape sequence for NUL, \021 is 17 in octal (the escape sequence for ^Q, a control character), and \012 is 10 in octal (\n).
as far as I know, the choice of \021 is arbitrary so long as there's one character before the "%s" part of the string.
unix["have"] is equivalent to 'a' (ascii code 0x61), so unix["have"]+"fun"-0x60 is equivalent to "fun"+1, which is just "un".
all this means that the program interpolates "un" into "%six\n\0", which is the string "unix\n\0".