Procedure

   shellc_c ( Shell sort a character array ) 

   void shellc_c ( SpiceInt     ndim,
                   SpiceInt     arrlen,
                   void       * array   )

Abstract

   Sort an array of character strings according to the ASCII
   collating sequence using the Shell Sort algorithm.

Required_Reading

   None.

Keywords

   ARRAY
   SORT

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   ndim       I   Dimension of the array.
   arrlen     I   String length.
   array     I-O  The array.

Detailed_Input

   ndim        is the number of elements in the array to be sorted.

   arrlen      is the declared length of the strings in the input
               string array, including null terminators. The input
               array should be declared with dimension

                  [ndim][arrlen]

   array       on input, is the array to be sorted.

Detailed_Output

   array       on output, contains the same elements, sorted
               according to the ASCII collating sequence.
               The actual sorting is done in place in array.

Parameters

   None.

Exceptions

   1)  If ndim < 2, this routine does not modify the array.

   2)  If the `array' input array pointer is null, the error
       SPICE(NULLPOINTER) is signaled.

   3)  If the `array' input array strings have length less than two
       characters, the error SPICE(STRINGTOOSHORT) is signaled.

Files

   None.

Particulars

   The Shell Sort Algorithm is well known.

Examples

   Let array contain the following elements:

      "FEYNMAN"
      "NEWTON"
      "EINSTEIN"
      "GALILEO"
      "EUCLID"
      "Galileo"

   Then after a call to shellc_c, the array would be ordered as
   follows:

      "EINSTEIN"
      "EUCLID"
      "FEYNMAN"
      "GALILEO"
      "Galileo"
      "NEWTON"

Restrictions

   1)  The input array is assumed to be sorted in increasing order. If
       this condition is not met, the results of bsrchc_c are unpredictable.

   2)  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)
   J. Diaz del Rio     (ODC Space)
   I.M. Underwood      (JPL)

Version

   -CSPICE Version 1.1.0, 05-AUG-2021 (JDR)

       Changed the input argument name "lenvals" to "arrlen" for consistency
       with other routines.

       Edited the header to comply with NAIF standard.

   -CSPICE Version 1.0.0, 18-JUL-2002 (NJB) (IMU)

Index_Entries

   shell sort a character array