It’s pretty funny to know this is valid C99 code, implementing a very basic array assignment and hello world:
%:include <stdio.h>
??=include <stdlib.h>
int main(int argc, char *argv<::>) ??<
int i??(:> = {1, 2, 3??>;
printf("Hello world\n");
return 0;
%>
It’s (ab)using an obscure feature in the C89 and C99 specifications called Trigraph and Digraph, when using GCC you need to pass the ‘-trigraphs’ parameter to enable this functionality. More information can be found on the Wikipedia page about it. I wonder whether people joining code obfuscation games use this.
