strtok.c

/*  $Id: strtok.c,v 1.1 1999/03/23 14:15:26 vickery Exp $
 *
 *    Replaces the library function of the same name.
 *
 *      This one tells you what the termination character was and
 *      where to continue scanning.
 *
 *      C. Vickery
 *      CS-381.2
 *      Spring 1999
 *
 *      $Log: strtok.c,v $
 * Revision 1.1  1999/03/23  14:15:26  vickery
 * Initial revision
 *
 */

#include <stdlib.h>
#include "strtok.h"

size_t strspn(  const char *s, const char *set );
size_t strcspn( const char *s, const char *set );

//  strtok()
//  ------------------------------------------------------------------
char *
strtok(       char  *whence,
        const char  *terms,
              char **next,
              char  *termch ) {

char  *token;


  //  See if there is work to do
  if ( whence == NULL || *whence == '\0' ) {

    *termch = '\0';
    *next = NULL;
    return NULL;

  }

  //  Do the work
  token = whence + strspn( whence, terms );
  if ( *token == '\0' ) {
    *termch = '\0';
    *next = NULL;
    return NULL;
  }
  *next  = token + strcspn( token,  terms );
  *termch = **next;

  //  See if there will be more work to do
  if ( **next != '\0' ) {
    *((*next)++) = 0;
  }

  //  Done
  return token;

}