C Preprocessor

A little "technique" that I came up with during an obfuscation challenge. There's no function recursion, but there is... file recursion?

noloop.c:

#if __INCLUDE_LEVEL__ == 0
int main() 
{
    puts("There is no loop...");
#endif
#if __INCLUDE_LEVEL__ <= 16
    puts(".. but Im in ur loop!");
    #include "noloop.c"
#else
    return 0;
}
#endif

C Preprocessor

A little "technique" that I came up with during an obfuscation challenge. There's no function recursion, but there is... file recursion?

noloop.c:

#if __INCLUDE_LEVEL__ == 0
int main() 
{
    puts("There is no loop...");
#endif
#if __INCLUDE_LEVEL__ <= 16
    puts(".. but Im in ur loop!");
    #include "noloop.c"
#else
    return 0;
}
#endif

I wrote/tested this using gcc. Obviously your compiler needs to support the __INCLUDE_LEVEL__ macro (or alternatively the __COUNTER__ macro with some tweaking) in order for this to compile. It should be fairly obvious how this works, but for fun, run the preprocessor without compiling the code (use the -E flag with gcc).