qsort -> please explain-it

I started my discussion in the above link, while copy and pasting the Quicksort Algorithm from "The C Programming Language, Second Edition" by Brian W. Kernighan and Dennis M. Ritchie (page 87).

And I rised a simple question, e.g. if we have these inputs: e.g. {11, 3, 9, 7, 4)

How this algorithm will work (just one iteration)! Believe me or not, no one was able to explain it

TERRIFYING! And I still have problem to understand it... well I am novice, dummy etc. But what about others?

Code:/* qsort: sort v[left]...v[right] into increasing order */ void qsort(int v[], int left, int right) { int i, last; void swap(int v[], int i, int j); if (left >= right) /* do nothing if array contains */ return; /* fewer than two elements */ swap(v, left, (left + right)/2); /* move partition elem */ last = left; /* to v[0] */ for (i = left + 1; i <= right; i++) /* partition */ if (v[i] < v[left]) swap(v, ++last, i); swap(v, left, last); /* restore partition elem */ qsort(v, left, last-1); qsort(v, last+1, right); } /* swap: interchange v[i] and v[j] */ void swap(int v[], int i, int j) { int temp; temp = v[i]; v[i] = v[j]; v[j] = temp; }