c program how qsort works? code example

Example 1: qsort in c

#include <stdlib.h>
int cmpfunc (const void * a, const void * b) {
   return ( *(int*)a - *(int*)b );
}

int main () {
//n is number of elements in arr(size f that arr)
   qsort(arr, n, sizeof(int), cmpfunc);
   }

Example 2: qsort c code

void qsort(void *base, size_t nitems, size_t size, int (*compar)(const void *, const void*))