#ifndef __SWAP_H__
#define __SWAP_H__

/**
 * Procedure:
 *   swap
 * Parameters:
 *   v, an array of pointers
 *   i, an integer
 *   j, an integer
 * Purpose:
 *   Swap the elements in positions i and j.
 * Produces:
 *   [Nothing; Called for the side effect]
 * Preconditions:
 *   0 <= i,j < length of v.
 *   X is v[i]
 *   Y is v[j]
 * Postconditions:
 *   v[i] is Y.
 *   v[j] is X.
 */
void swap (void *v[], int i, int j);

#endif // __SWAP_H__