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@Fast-Nop YES! Sorry you are right, I was pretty tired last night and forgot to put the actual third item inside of the array. The example I am talking about is:
@highlight
int items[] = {1, 2, 3, 4};
printf("%i\n", 3[items]); // this is the one that correctly gives back the number at index 3 -
@Fast-Nop btw bud, you are our C wiz here, do you know of other black magic items that exist inside of the language?
I have a passion for C, even though I have literally no projects in real life to apply it other than my own academic interests. -
@AleCx04 Duff's Device https://en.wikipedia.org/wiki/... is pretty crazy shit.
Then there's computed goto as GCC/Clang extension where you have an array of function-local labels and can goto-jump via the array index - I'd love to see that adopted in the C standard.
If you consider goto as already bad, then setjmp/longjmp for exception handling in C will probably blow your fuses. That lets you jump upwards in the call stack.
What's also nice is how to abuse extern array declarations for faking #error in conjunction with sizeof. Basically, you declare an array as extern whose size is either 1 or -1, depending on whether the sizeof stuff boils out or not. Since it's extern, it won't take actual space if it compiles, it's just a useless declaration.
Finally, you can even abuse the C preprocessor as static website generator, that's really sick: https://accu.org/journals/overload/... -
@Fast-Nop I am stuck trying to understand duff's device, didn't even knew what loop unrolling was, looking at videos now.
This shit is crazy, I love it and need more -
@AleCx04 In a loop, you have the actual loop body which does the work, and the loop overhead at the end of the loop to check the loop condition and make a conditional branch back to the top of the loop.
If the body is short, then the overhead is considerable. So what you do is copy-paste the body N times and run the loop only 1/N times. That saves you (N-1)/N of the overhead.
However, what if the actual loop length isn't divisible by N? Then you have to deal with the leftover loop runs. You can append a second loop for that - e.g. if you unroll by N=8, you can AND the original loop length with 0x07 and use that as loop length for this second loop. Or you can use the Duff's Device hack.
When it comes to the idea of programming and magic, or the comparison between software developers/engineers, computer scientists etc as magicians or wizards, nothing brings the idea much more close to hearth than the C programming language.
A while ago I read the R.A Salvatore books concerning Drizzt, the dark elf. I loved the books, have not continued reading them but I remember them vividly. There was one book in which a human magician came about wielding extremely explosive magic, humans were capable of channeling large amounts of it through explosive and unwieldly ends.
This is the same feeling I get from C
Consider:
int items[] = {1, 2, 3};
printf("Third : %i\n", 3[items]);
and fuck me if shit like the above is not dangerous, it makes sense, arrays have the first items of it server as the pointer address to a first element, doing the above operation returns the third element of the array of 3. But holy shit if I don't think this is dangerous and interesting as fuck
there are many more examples I have that I am finding through me fucking around with: language development (compiler, interpreter), kernel programming as well as net sec. C is the most powerful and devastating thing we have in our hands indeed.
random
c is black magic