Quicksort partitioning - sorting

Question

I am sorry to be dumb, but I have been struggling with my own quicksort implementation for quiet a while. To be more specific, I can't get my partition procedure to work properly. Ridiculously enough, but I've also tried to almost directly copy an implementation from Sedjewick's book, with no success, however.
Here is my code:
void partition(int a[], int size)
{
int i, j = size - 1;
int t, pivot = a[j / 2];
i = 0;
for (;;)
{
while (a[i] < pivot)
i++;
while (a[j] > pivot)
j--;
if (i >= j)
break;
t = a[i];
a[i++] = a[j];
a[j] = t;
}
}
Here is the example of input:
82, 65, 59, 10, 35, 51, 81, 47, 25, 64, 34, 38, 12, 38, 58, 74, 37, 42, 63, 18,
75, 67, 36, 77, 47, 48, 13, 91, 94, 52
The pivot here is 58, but I get wrong output:
52, 13, 48, 10, 35, 51, 47, 47, 25, 36, 34, 38, 12, 38, 18, 58, 37, 42, 63, 74,
75, 67, 64, 77, 81, 59, 65, 91, 94, 82
It looks almost correct, with a little exception of 37 and 42 going right after 58. I've tried a lot of variations of partitioning procedure, but they all get me similar results.

Answer 1

EDIT
My previous answer seemed to fix the issue but wasn't correct.
Your output is fine. Let me visually indicate the partition with vertical bars:
52, 13, 48, 10, 35, 51, 47, 47, 25, 36, 34, 38, 12, 38, 18, 58, 37, 42 || 63, 74, 75, 67, 64, 77, 81, 59, 65, 91, 94, 82
Everything to the left of the vertical bars is <= 58, and everything to the right is >= 58. This is what's expected from the partition step in a quicksort.
You do, however, need to decrement j in addition to incrementing i:
t = a[i];
a[i++] = a[j];
a[j--] = t; // added a decrement here
Other than that, the only thing you're missing is returning the partition index. Simply return the value of i at the end of the function and use that as the array boundary in your recursive step.

Answer 2

Replace a[j] = t; with a[j--] = t