dt_Handle pattern, molecule, pathset, container;
  dt_Integer slen, pcount, acount, bocunt;
  dt_String str;

  /* Read SMARTS in. */
  pattern = dt_smartin(2, "Oa");

  /* Optimized for matches on typical molecules. */
  str = dt_smarts_opt(&slen, 2, "aO", 0);
  printf("The optimized SMARTS expression is %.*s.\n", slen, str);

  /* The aromatic oxygen pattern and hydroquinone have
    matching paths. */
  molecule = dt_smilin(12, "Oc1ccc(O)cc1");
  pathset = dt_match(pattern, molecule, 0);

  /* There are two oxygen-aromatic paths in hydroquinone. */
  pcount = dt_count(pathset, TYP_PATH);
  printf("There are %d oxygen-aromatic atom paths in hydroquinone.\n", pcount);

  /* The oxygen-aromatic path contains 2 atoms and 1 bond. */
  acount = dt_count(pathset, TYP_ATOM);
  bcount = dt_count(pathset, TYP_BOND);
  printf("The oxygen-aromatic path contains %d atoms and %d bond.\n",
      acount/pcount, bcount/pcount);

  /* The pathset refers to the molecule as its base. */
  if (dt_base(pathset) == molecule)
    printf("You can access the molecule through the pathset.\n");

  /* Stream the pathset. */
  container = dt_stream(pathset, TYP_PATH);
  /* The unique identifiers (uid) of the atoms and bond
    reflect their position in the input SMILES string. */

 
{
   
dt_Handle path1, pathX, container2, object;
   
dt_Integer uid;
   
int i, j;

   
i=0;
   
while (NULL_OB != (pathX = dt_next(container))) {
     
if (0 == i)
       
path1 = pathX;
     
i++;
     
j=0;
     
container2 = dt_stream(pathX, TYP_ANY);
     
while (NULL_OB != (object = dt_next(container2))) {
       
j++;
       
str = dt_typename(&slen, object);
       
uid = dt_uid(object);
       
printf("Path %d object %d is type %.*s with uid %d\n",
             
i, j, slen, str, uid+1);
     
}
   
}
 
}

 
/* A reset and next operation gives the first path again. */
 
dt_reset(container);
 
pathX = dt_next(container);
 
if (pathX == path1)
   
printf("Reset is like rewind.\n");

 
/* Each path refers to the molecule as its base. */
 
if (dt_base(pathX) == molecule)
   
printf("You can access the molecule through the path.\n");

(selected output)

Path 1 object 1 is type atom with uid 1
Path 1 object 2 is type bond with uid 1
Path 1 object 3 is type atom with uid 2
Path 2 object 1 is type atom with uid 6
Path 2 object 2 is type bond with uid 6
Path 2 object 3 is type atom with uid 5

The optimized SMARTS expression is Oa.
There are 2 oxygen-aromatic atom paths in hydroquinone.
The oxygen-aromatic path contains 2 atoms and 1 bond.
You can access the molecule through the pathset.
Path 1 object 1 is type atom with uid 1
Path 1 object 2 is type bond with uid 1
Path 1 object 3 is type atom with uid 2
Path 2 object 1 is type atom with uid 6
Path 2 object 2 is type bond with uid 6
Path 2 object 3 is type atom with uid 5
Reset is like rewind.
You can access the molecule through the path.