Comments on Loopy C Puzzle

Ryan said:

int i;
for (i = 0; abs(i) < 6; i--) {
    printf(".");
}

Ryan said:

int i;
for (i = 0; -i < 6; i--) {
    printf(".");
}

Sean said:

Changing the loop condition to i ^= 6; is another solution.

Ryan said:

Ah-ha, a tricky one:

int i;
for (i = 0; i ^= 6; i--) {
    printf(".");
}

Ryan said:

Ah, Sean beat me to it. :(

Martin DeMello said:

for (i = 0; i + 6; i--)

will stop when i + 6 = 0.

John Tromp said:

The value in variable i decrements to INT_MIN after |INT_MIN| + 1 iterations.

No; i decrements to INT_MIN after |INT_MIN| iterations. For example, if i were a signed 1-bit integer, making INT_MIN equal to -1, than i becomes -1 upon executing --i after the first iteration.

Of course, you're correct that |INT_MIN| + 1 dots are output, due to the extra (and final) iteration starting with i = INT_MIN.