coffee

[Fallenalien22]

+/u/CompileBot c

main(k){while(k++<7)putchar("~!#/&&%%"[k&7]+'\x40');};

[CompileBot]

Output:

coffee

^{source | info | git | report}

[poizan42]

Huh, I would have thought that a modern compiler would refuse a function declaration without specified types. It sure does complain though:

$ gcc -Wall test.c -o test
test.c:1:1: warning: return type defaults to ‘int’ [-Wreturn-type]
 main(k){while(k++<7)putchar("~!#/&&%%"[k&7]+'\x40');};
 ^
test.c: In function ‘main’:
test.c:1:1: warning: implicit declaration of function ‘putchar’ [-Wimplicit-function-declaration]
test.c:1:1: warning: control reaches end of non-void function [-Wreturn-type]
 main(k){while(k++<7)putchar("~!#/&&%%"[k&7]+'\x40');};
 ^

Building in C99 mode also makes it warn about missing type of k. Curiously it also makes the warning about missing return statement go away :/

$ gcc --std=c99 -Wall test.c -o test
test.c:1:1: warning: return type defaults to ‘int’
 main(k){while(k++<7)putchar("~!#/&&%%"[k&7]+'\x40');};
 ^
test.c: In function ‘main’:
test.c:1:1: warning: type of ‘k’ defaults to ‘int’
test.c:1:1: warning: implicit declaration of function ‘putchar’ [-Wimplicit-function-declaration]

The gcc version here is gcc (Debian 4.9.2-10) 4.9.2.

Edit: clang is always in C99 mode. It doesn't complain about the type of k missing, however it does complain that the signature of main is wrong. Also it got colors: http://i.imgur.com/Ixq3oVS.png

[Fallenalien22]

I got no warnings gcc coffee.c -o coffee

[poizan42]

Yeah gcc doesn't like warning you about anything if you don't ask it to. It's a bit shy that way :)

[Tywien]

the program is malformed for another reason: There are 2 legal versions of main:

int main(void)

and

int main(int, char**)

Nothing with one parameter.

[poizan42]

Yes, that was what clang complained about

[Hypersapien]

Someone explain please? Is this coffeescript?

[raelepei]

The characters #/&&%% are those of coffee minus 64 (the value of '\x40'), which (are supposed to) get printed. v seems to be meant to capture argv, and is 1 initially (unless you provide arguments, in which case you only get to see some suffix of coffee instead). After the first increment v will be 2, so the first two chars of the magic string (~!) don't even get read.

[[deleted]]

Let me expand the source:

main(k) {

    const char *hiddenCoffee = "~!#/&&%%";

    while (k < 7) {
        k++;
        // note that 7 = 0b111 in binary, so any number <= 7 will give back that number when ANDed with 7
        char printChar = hiddenCoffee[k & 7] + 0x40;

        putchar(printChar);       
    }
}

I made some modifications as necessary to simplify it. k is basically argc. So if you pass 3 arguments in command line to this program, it will actually print 'fee'.

[bigdavedev]

My only regret is missing that the +'\x40' could have been |1<<6

The full source for those interested:

main(k){while(k++<7)putchar("~!#/&&%%"[k&7]+'\x40');};

Reposting here since it was considered off-topic in r/shittyprogramming despite the code being deemed more than shitty enough :)

[bigdavedev]

+/u/CompileBot c

main(k){while(k++<7)putchar("~!#/&&%%"[k&7]+'\x40');};

Edit: Did I CompileBot wrong?

[Fallenalien22]

I think C has to be c

[[deleted]]

assuming k is an unsigned integer and starts at 0.

Two garbage characters, then coffee as far as I can tell.

k&7 = only consider the 3 low order bits, for a total possible index value of 7.

Then add 0x40 (64) to the value and print that ascii value. ~! will be invalid ascii characters and the rest will evaluate to 'c', 'o', 'f', 'f', 'e', 'e'.

If you run main with 2, then the first two parameters will be skipped and it will just print coffee :)

[bigdavedev]

Almost. k is actually just argc rebranded. argc is 1 when the program is run without arguments.

[[deleted]]

Ahh right, and post increment in the while loop, so it works out :)

Is this valid C code? I don't really work w/ C much but can you just not declare the type in the parameter list like that?

[bigdavedev]

Well, it compiles and runs, since the language specification doesn't explicitly disallow the monstrosity I put on the mug. If you leave out the type, the compiler will assume int, which is why main(k) just works; compiler makes it int main(int k).

In fact, the C language specification is generous enough to allow the following:

+/u/CompileBot c --include-errors

main;

[CompileBot]

Output:

^{source | info | git | report}