Code Golf: Tic Tac Toe

Answer 1

C, 99 chars

Not a winner, but maybe there's room for improvement. Never did this before. Original concept, first draft.

#define l w|=*b&b[s]&b[2*s];b+=3/s;s
f(int*b){int s=4,w=0;l=3;l;l;l=2;--b;l=1;b-=3;l;l;return l;}

Thanks to KennyTM for a few ideas and the test harness.

The "development version":

#define l w|=*b&b[s]&b[2*s];b+=3/s;s // check one possible win
f( int *b ) {
        int s=4,w=0; // s = stride, w = winner
        l=3;     // check stride 4 and set to 3
        l;l;l=2; // check stride 3, set to 2
        --b;l=1; // check stride 2, set to 1
        b-=3;l;l; return l; // check stride 1
}