/* cansmi_tutorial.c */

    /**********************************************************************
    * This source code is public domain, and may be freely distributed,	  *
    * modified, and used for any purpose.  IT COMES WITH ABSOLUTELY NO    *
    * WARRANTY OF ANY KIND.						  *
    **********************************************************************/

/*****************************************************************************
*  cansmi.c -- the "Hello World" of Daylight toolkit programming.
*/

#include <stdio.h>
#include <string.h>

/*** This defines Daylight constants such as "dt_Handle" and function
  prototypes.  These are required for Daylight toolkit programs. ***/

#include "dt_smiles.h"

int main(int argc, char *argv[])
{

  /*** A dt_Handle is one of the special datatypes used by the
       Daylight toolkit.  All Daylight toolkit functions use these
       types;  in this case a dt_Handle is the ID of an object
       within the toolkit.  The value has no meaning on it's own,
       but is used to refer to an object. ***/

  dt_Handle mol;

  int       lencan;
  char      *cansmi, line[1000];

  while (gets(line)) {

    /*** dt_smilin() parses a SMILES string and attempts to make
         a molecule or reaction object from it.  If it succeeds it
         returns the ID of the new object that was created, which
         we store in a local variable.  If it fails the function
         returns the special constant "NULL_OB" ***/

    mol = dt_smilin(strlen(line), line);
    if (mol == NULL_OB)
      fprintf(stderr, "ERROR: Can't parse \"%s\"\n", line);
    else {

      /*** The dt_cansmiles() function asks the molecule (or reaction)
           to compute it's canonical SMILES and return it.  If it fails
           it returns the "invalid string", which in the C language is
           NULL. ***/

      cansmi = dt_cansmiles(&lencan, mol, 0);
      if (cansmi && (lencan > 0))
        printf("%.*s\n", lencan, cansmi);
      else
        fprintf(stderr, "ERROR: Can't make unique SMILES for \"%s\"\n", line);

      /*** dt_dealloc() releases the resources used by the object.  Generally
           a good idea.  Once an object has been deallocated, referring to
           it by it's handle is an error.  ***/

      dt_dealloc(mol);
    }
  }
  return 0;
}