Index Page ordc_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
       SpiceInt ordc_c ( ConstSpiceChar  * item,
                         SpiceCell       * set   )
#### Abstract
       The function returns the ordinal position of any given item in a
       character set.  If the item does not appear in the set, the function
       returns -1.
#### Required_Reading
       SETS
#### Keywords
       SEARCH
       SETS
#### Brief_I/O
       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       item       I   An item to locate within a set.
       set        I   A set to search for a given item.

       The function returns the ordinal position of item within the set.
#### Detailed_Input
       item      is a character string to be located within a set.
                 Trailing blanks are not significant in the comparison.

       set       is an integer CSPICE set that is to be searched for the
                 occurrence of item.  Trailing blanks are not significant
                 in the comparison.

                 set must be declared as a character SpiceCell.
#### Detailed_Output
       The function returns the ordinal position of item within set.
       Ordinal positions range from 0 to N-1, where N is the cardinality
       of the set.

       If item is not an element of set, the function returns -1.
#### Parameters
       None.
#### Exceptions
       1) If the input set argument is a SpiceCell of type other than
          character, the error SPICE(TYPEMISMATCH) is signaled.

       2) If the input set argument does not qualify as a CSPICE set,
          the error SPICE(NOTASET) will be signaled.  CSPICE sets have
          their data elements sorted in increasing order and contain
          no duplicate data elements.

       3) If the input string pointer is null, the error SPICE(NULLPOINTER)
          is signaled.
#### Files
       None.
#### Particulars
       A natural ordering can be imposed upon the elements of any
       CSPICE set, be it integer, character or double precision.  For
       character strings the ASCII collating sequence serves as the
       ordering relation, for double precision and integer variables
       the arithmetic ordering is used.

       Given any element of a set, its location within this ordered
       sequence of elements is called its ordinal position within
       the set.

       In common mathematical usage, ordinal positions of elements
       in a set of cardinality N range from 1 to N.  In C programs,
       it is much more convenient to use the range 0 to N-1; this is
       the convention used in CSPICE.

       For illustrative purposes suppose that set represents the set

          { "8", "1", "2", "9", "7", "4", "10" }

       The ordinal position of:

           "8" is 5
           "1" is 0
           "2" is 2
           "9" is 6
           "7" is 4
           "4" is 3
          "10" is 1
#### Examples
       1) Obtain the ordinal positions shown in the table of the Particulars
          section above.

             #include "SpiceUsr.h"

             int main()
             {
                /.
                Declare an integer set and populate it with the elements
                shown above.
                ./
                #define MAXSIZ         7
                #define ITMLEN         10

                SPICECHAR_CELL ( set, MAXSIZ, ITMLEN );

                SpiceChar            * cElt;

                SpiceChar              inputs [MAXSIZ][ITMLEN] =
                                       {
                                          "8", "1", "2", "9", "7", "4", "10"
                                       };

                SpiceInt               expected [MAXSIZ] =
                                       {
                                          5, 0, 2, 6, 4, 3, 1
                                       };

                SpiceInt               i;

                /.
                Create the set.
                ./

                for ( i = 0;  i < MAXSIZ;  i++ )
                {
                   insrtc_c ( inputs[i], &set );
                }

                /.
                Examine the ordinal positions of the set's elements.
                Extract each element and verify that ordc_c gives the
                index at which the element is located.
                ./

                for ( i = 0;  i < card_c(&set);  i++ )
                {
                   cElt = inputs[i];

                   if (  ordc_c(cElt, &set)  !=  expected[i]  )
                   {
                      setmsg_c ( "Position of # was expected to be # "
                                 "but was actually #."                 );
                      errch_c  ( "#",  cElt                            );
                      errint_c ( "#",  expected[i]                     );
                      errint_c ( "#",  ordc_c(cElt,&set)               );
                      sigerr_c ( "INVALID LOCATION"                    );
                   }
                }

                return ( 0 );
             }
#### Restrictions
       1)  String comparisons performed by this routine are Fortran-style:
           trailing blanks in the input array or key value are ignored.
           This gives consistent behavior with CSPICE code generated by
           the f2c translator, as well as with the Fortran SPICE Toolkit.

           Note that this behavior is not identical to that of the ANSI
           C library functions strcmp and strncmp.
#### Literature_References
       None.
#### Author_and_Institution
       N.J. Bachman    (JPL)
       C.A. Curzon     (JPL)
       H.A. Neilan     (JPL)
       W.L. Taber      (JPL)
       I.M. Underwood  (JPL)
#### Version
       -CSPICE Version 1.0.0, 21-AUG-2002 (NJB) (CAC) (HAN) (WLT) (IMU)
#### Index_Entries
       the ordinal position of an element in a set
#### Link to routine ordc_c source file ordc_c.c

    Wed Jun  9 13:05:27 2010