Index Page daffna_c
A B C D E F G H I J K L M N O P Q R S T U V W X
Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries
#### Procedure
       void daffna_c ( SpiceBoolean  * found )
#### Abstract
       Find the next (forward) array in the current DAF.
#### Required_Reading
       DAF
#### Keywords
       FILES
#### Brief_I/O
       Variable  I/O  Description
       --------  ---  --------------------------------------------------
       found      O   SPICETRUE if an array was found.
#### Detailed_Input
       None.
#### Detailed_Output
       found       is SPICETRUE if an array was found, and is SPICEFALSE
                   if, when this routine is called, the current array is
                   the tail of the array list.  (Recall that the arrays in
                   a DAF may be viewed as a doubly linked list, with the
                   tail being the last array in the file.)
#### Parameters
       None.
#### Exceptions
       1)  If this routine is called before a search is begun, the
           error SPICE(DAFNOSEARCH) is signalled.

       2)  If the DAF to be searched has actually been closed, the error
           will be diagnosed by routines called by this routine.

       3)  If the end of the array list has already been reached when
           this routine is called, this routine has no effect.
#### Files
       None.
#### Particulars
       The DAF search routines are:

          dafbfs_c       Begin forward search.
          daffna         Find next array.

          dafbbs_c       Begin backward search.
          daffpa_c       Find previous array.

          dafgs_c        Get summary.
          dafgn_c        Get name.
          dafgh_c        Get handle.

          dafcs_c        Continue search.

       The main function of these entry points is to allow the
       contents of any DAF to be examined on an array-by-array
       basis.

       Conceptually, the arrays in a DAF form a doubly linked list,
       which can be searched in either of two directions: forward or
       backward. It is possible to search multiple DAFs simultaneously.

       dafbfs_c (begin forward search) and daffna are used to search the
       arrays in a DAF in forward order.  In applications that search a
       single DAF at a time, the normal usage is

          dafbfs_c ( handle );
          daffna_c ( &found );

          while ( found )
          {
             dafgs_c ( sum  );
             dafgn_c ( name );
              .
              .

             daffna_c ( &found );
          }

       dafbbs_c (begin backward search) and daffpa_c are used to search the
       arrays in a DAF in backward order.  In applications that search
       a single DAF at a time, the normal usage is

          dafbbs_c ( handle );
          daffpa_c ( &found );

          while ( found )
          {
             dafgs_c ( sum  );
             dafgn_c ( name );
              .
              .

             daffpa_c ( &found );
          }

       In applications that conduct multiple searches simultaneously,
       the above usage must be modified to specify the handle of the
       file to operate on, in any case where the file may not be the
       last one specified by dafbfs_c or dafbbs_c.  The routine dafcs_c
       (DAF, continue search) is used for this purpose.  Below, we
       give an example of an interleaved search of two files specified
       by the handles handl1 and handl2.  The directions of searches
       in different DAFs are independent; here we conduct a forward
       search on one file and a backward search on the other.
       Throughout, we use dafcs to specify which file to operate on,
       before calling daffna_c, daffpa_c, dafgs_c, or dafgn_c.

          dafbfs_c ( handl1 );
          dafbbs_c ( handl2 );

          dafcs_c  ( handl1  );
          daffna_c ( &found1 );

          dafcs_c  ( handl2  );
          daffpa_c ( &found2 );

          while ( found1 || found2 )
          {
             if ( found1 )
             {
                dafcs_c ( handl1 );
                dafgs_c ( sum    );
                dafgn_c ( name   );
                 .
                 .
                dafcs_c  ( &handl1 );
                daffna_c ( &found1 );
             }

             if ( found2 )
             {
                dafcs_c ( handl2 );
                dafgs_c ( sum    );
                dafgn_c ( name   );
                 .
                 .
                dafcs_c  ( handl2  );
                daffpa_c ( &found2 );
             }
          }

       At any time, the latest array found (whether by daffna_c or daffpa_c)
       is regarded as the "current" array for the file in which the
       array was found.  The last DAF in which a search was started,
       executed, or continued by any of dafbfs_c, dafbbs_c, daffna_c,
       daffpa_c or dafcs_c is regarded as the "current" DAF.  The summary
       and name for the current array in the current DAF can be obtained
       separately, as shown above, by calls to DAFGS (get summary) and
       dafgn_c (get name).  The handle of the current DAF can also be
       obtained by calling dafgh_c (get handle).

       Once a search has been begun, it may be continued in either
       direction. That is, daffpa_c may be used to back up during a
       forward search, and daffna_c may be used to advance during a
       backward search.
#### Examples
       1) See Particulars.
#### Restrictions
       None.
#### Literature_References
       NAIF Document 167.0, "Double Precision Array Files (DAF)
       Specification and User's Guide"
#### Author_and_Institution
       N.J. Bachman    (JPL)
       W.L. Taber      (JPL)
       I.M. Underwood  (JPL)
#### Version
       -CSPICE Version 1.0.0, 31-JUL-1999 (NJB) (WLT) (IMU)
#### Index_Entries
       find next daf array
#### Link to routine daffna_c source file daffna_c.c

    Wed Jun  9 13:05:20 2010