Procedure

     PREFIX (Prefix a character string)

     SUBROUTINE PREFIX ( PREF, SPACES, STRING )

Abstract

     Add a prefix to a character string.

Required_Reading

     None.

Keywords

     ASSIGNMENT
     CHARACTER
     STRING

Declarations

     IMPLICIT NONE

     CHARACTER*(*)    PREF
     INTEGER          SPACES
     CHARACTER*(*)    STRING

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     PREF       I   Prefix.
     SPACES     I   Number of spaces separating prefix and suffix.
     STRING    I-O  Suffix on input, string on output.

Detailed_Input

     PREF     is the prefix to be added to the string. Trailing
              blanks are ignored. (A blank prefix is interpreted
              as a null prefix.)

     SPACES   is the number of spaces (blanks) in the output
              string separating the last non-blank character
              of the prefix from the first (blank or non-blank)
              character of the suffix. Typically, this will be
              zero or one. If not positive, SPACES defaults to
              zero.

     STRING   on input is the suffix to which the prefix is to
              be added. Leading blanks are significant.

Detailed_Output

     STRING   on output is the is the prefixed string. If STRING
              is not large enough to contain the output string,
              the output string is truncated on the right.

              STRING may NOT overwrite PREF.

Parameters

     None.

Exceptions

     Error free.

     1)  If SPACES is negative it is treated as zero.

Files

     None.

Particulars

     The suffix is shifted to the right to make room for the prefix
     and required spaces, which are then added to the front of the
     string. (The shift operation handles any necessary truncation.)

Examples

     The following examples illustrate the use of PREFIX.

           PREF         STRING (input)   SPACES    STRING (output)
           ----------   --------------   ------    ---------------
           'abc     '   'def    '             0    'abcdef '
           'abc     '   'def    '             1    'abc def'
           'abc     '   ' def   '             0    'abc def'
           'abc     '   ' def   '             1    'abc  de'
           ' abc    '   'def    '             0    ' abcdef'
           ' abc    '   'def    '             1    ' abc de'
           ' abc    '   ' def   '            -1    ' abc de'
           '        '   'def    '             0    'def    '
           '        '   'def    '             1    ' def   '
           ' abc    '   '       '             0    ' abc   '

Restrictions

     1)  PREF and STRING must be distinct.

Literature_References

     None.

Author_and_Institution

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

Version

    SPICELIB Version 1.1.0, 18-MAR-2021 (JDR)

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard.

    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 (WLT) (IMU)