Different results when using increment operator (arr[i++] vs arr[i]; i++;)

I can't get my head around why the code below is not working as expected:

#include <stdio.h>

int main() {
    int i = 0, size = 9, oneOrZero[] = {1,1,1,1,1,1,1,1,0};
    while (i < size && oneOrZero[i++]);
    if (i == size) printf("All ones"); else printf("Has a zero");
}

Terminal: All ones.

When incrementing the index inside the loop makes the code run as expected:

#include <stdio.h>

int main() {
    int i = 0, size = 9, oneOrZero[] = {1,1,1,1,1,1,1,1,0};
    while (i < size && oneOrZero[i]) {i++;}
    if (i == size) printf("All ones"); else printf("Has a zero");
}

Terminal: Has a zero.

Could someone explain the difference between these two?

In the first code, when i is 8, oneOrZero[i] will evaluate to false because oneOrZero[8] == 0, but i will be incremented to 9 anyway, the increment is not dependent on the truthiness of the expression, it will happen as many times as the expression is evaluated.

So naturally when i == size is evaluated it's 9 == 9, this is, of course, true, therefore "All ones" will be printed giving you the wrong output.

In the second code i is incremented inside the body of the conditional expression, this means it will only be incremented if the condition is met, so when i is 8, oneOrZero[i] will evaluate to false and i is not incremented, retaining its 8 value.

In the next line statement i == size will be 8 == 9 which is false and "Has a zero" will be printed, giving you the correct output.