How is this possible?

Question

In following code there is declaration even before the block beginning of the main function. Is this allowed?

long long n,u,m,b;
main(e,r)
    char **r; //<<<Is this possible???
{
    for( ; n++ || (e=getchar()|32)>=0 ; b="ynwtsflrabg"[n%=11]-e?b:b*8+n)
        for( r=b%64-25 ; e<47&&b ; b/=8)
            for( n=19; n ; n["1+DIY/.K430x9G(kC["]-42&255^b||(m+=n>15?n:n>9?m%u*~-u:~(int)r?n+!(int)r*16:n*16,b=0))
            u=1ll<<6177%n--*4;printf("%llx\n",m);
}

Source: I found this code on ioccc.org

int `main(e,r)char **r;{` , `r` is **not** global but function parameter you can do this in ansi-C. Where as `n,u,m,b;` are global variables. — Grijesh Chauhan, Aug 24 '13 at 17:22
Was `long long n,u,m,b;` before `main` your only doubt ? If yes, you picked a really bad example. — P0W, Aug 24 '13 at 17:24
@Renan I would have asked the same question even after finding out for myself, just to get some outside perspective about **why** it works. I find this question fascinating, and I certainly don't think it's off topic. — Michael Dorst, Aug 24 '13 at 19:29
Also, the OP is **not asking for code**. Therefore the reason given for closing this question is **not applicable**. — Michael Dorst, Aug 24 '13 at 19:33

score 6 · Answer 1 · answered Aug 24 '13 at 17:20

Yes, C allows declarations outside of functions. These declarations define global or static variables (you need a static modifier for that).

Re-formatting your program produces this:

long long n,u,m,b;
main(e,r)
    char **r; // Pre-ANSI parameter declarations; do not do that in new programs!
{
    for( ; n++ || (e=getchar()|32)>=0 ; b="ynwtsflrabg"[n%=11]-e?b:b*8+n)
        for( r=b%64-25 ; e<47&&b ; b/=8)
            for( n=19; n ; n["1+DIY/.K430x9G(kC["]-42&255^b||(m+=n>15?n:n>9?m%u*~-u:~(int)r?n+!(int)r*16:n*16,b=0))
                u=1ll<<6177%n--*4;printf("%llx\n",m);
}

There's some serious obfuscation going on here, but syntactically it's valid code.

Can you help me understand what's going on between `main` and the first `{`? How come `e` has no type? — Michael Dorst, Aug 24 '13 at 17:29
@anthropomorphic Ref: -http://stackoverflow.com/a/18422382/1870232 — P0W, Aug 24 '13 at 19:56

How is this possible?

1 Answers1