Procedure

     CYCLEC ( Cycle a character string )

     SUBROUTINE CYCLEC ( INSTR, DIR, NCYCLE, OUTSTR )

Abstract

     Cycle the contents of a character string to the left or right.

Required_Reading

     None.

Keywords

     CHARACTER
     UTILITY

Declarations

     IMPLICIT NONE

     CHARACTER*(*)      INSTR
     CHARACTER*1        DIR
     INTEGER            NCYCLE
     CHARACTER*(*)      OUTSTR

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     INSTR      I   String to be cycled.
     DIR        I   Direction to cycle.
     NCYCLE     I   Number of times to cycle.
     OUTSTR     O   Cycled string.

Detailed_Input

     DIR      is the direction in which the characters in the
              string are to be cycled.

                    'L' or 'l'  to cycle left.
                    'R' or 'r'  to cycle right.

     NCYCLE   is the number of times the characters in the string
              are to be cycled.

     INSTR    is the string to be cycled.

Detailed_Output

     OUTSTR   is the input string after it has been cycled.

Parameters

     None.

Exceptions

     1)  If the direction flag is not one of the acceptable values
         'r', 'R', 'l', 'L',  the error SPICE(INVALIDDIRECTION) is
         signaled.

Files

     None.

Particulars

     A string is cycled when its contents are shifted to the left
     or right by one place. A character pushed off one end of the
     string is brought around to the other end of the string instead
     of disappearing.

     Leading and trailing blanks are treated just like any other
     characters.

     If the output string is not large enough to contain the input
     string, the cycled string is truncated on the right.

Examples

     'abcde'   cycled left twice becomes               'cdeab'
     'abcde '  cycled left twice becomes               'cde ab'
     'abcde'   cycled right once becomes               'eabcd'
     'Apple '  cycled left six times becomes           'Apple '
     'Apple '  cycled right twenty-four times becomes  'Apple '

Restrictions

     1)  The memory used for the output string must be identical to
         that used for the input string or be disjoint from the input
         string memory.

         That is:

            CALL CYCLEN ( STRING, DIR, NCYCLE, STRING )

         will produce correct results with output overwriting input.

            CALL CYCLEN ( STRING(4:20), DIR, NCYCLE, STRING(2:18) )

         will produce garbage results.

Literature_References

     None.

Author_and_Institution

     J. Diaz del Rio    (ODC Space)
     W.L. Taber         (JPL)
     I.M. Underwood     (JPL)

Version

    SPICELIB Version 1.2.0, 12-AUG-2021 (JDR)

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard.

    SPICELIB Version 1.1.0, 18-JUN-1999 (WLT)

        Fixed problem with unbalanced CHKIN/CHKOUT calls.

    SPICELIB Version 1.0.1, 10-MAR-1992 (WLT)

        Comment section for permuted index source lines was added
        following the header.

    SPICELIB Version 1.0.0, 31-JAN-1990 (IMU) (WLT)