Procedure

   nthwd_c ( n'th word in a character string ) 

   void nthwd_c  ( ConstSpiceChar    * string,
                   SpiceInt            nth,
                   SpiceInt            worlen,
                   SpiceChar         * word,
                   SpiceInt          * loc    )

Abstract

   Return the nth word in a character string, and its location
   in the string.

Required_Reading

   None.

Keywords

   CHARACTER
   PARSING
   SEARCH
   WORD

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   string     I   Input character string.
   nth        I   Index of the word to be returned.
   worlen     I   Maximum length of output string `word'.
   word       O   The `nth' word in `string'.
   loc        O   Location of `word' in `string'.

Detailed_Input

   string      is a null-terminated string to be parsed. Each word of this
               string is a maximal sequence of consecutive non-blank, non-null
               characters.

   nth         is the index of the word to be returned. (Zero for the first
               word, one for the second, and so on.)

   worlen      is the maximum allowed length of the output string `word'.
               This length must be large enough to hold the output string
               plus the null-terminator character. If the output string
               is expected to have N characters, `worlen' should be at
               least N+1.

Detailed_Output

   word        is the n'th word in `string'. If `string' is blank or empty,
               or `nth' is non-positive or too large, `word' is empty.

               If the n'th word is longer than worlen-1 characters, it will be
               truncated on the right.

               `word' may overwrite `string'.

   loc         is the location of `word' in `string'. (That is, `word'
               begins at string[loc]). If `string' is blank or empty, or
               `nth' is nonpositive or too large, `loc' is -1.

Parameters

   None.

Exceptions

   1)  If the declared length of `word' is not large enough to contain
       the `nth' word in `string', the word will be truncated on the
       right.

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

   3)  If the `word' output string pointer is null, the error
       SPICE(NULLPOINTER) is signaled.

   4)  If the `word' output string has length less than two
       characters, the error SPICE(STRINGTOOSHORT) is signaled, since
       the output string is too short to contain one character of
       output data plus a null terminator.

Files

   None.

Particulars

   nthwd_c, like nextwd_c, is useful primarily for parsing input commands
   consisting of one or more words, where a word is defined to be a
   maximal sequence of consecutive non-blank, non-null characters. Each word is
   bounded on both sides by a blank character, or by the start or end
   of the input string. Successive calls to nextwd_c allow the calling
   routine to neatly parse and process one word at a time.

   The chief difference between the two routines is that
   nthwd_c allows the calling routine to access the words making
   up the input string in random order. (nextwd_c allows only
   sequential access.)

   nthwd_c may be more efficient than nextwd_c, since nthwd_c doesn't
   update an output string consisting of the remaining, unparsed
   string.

Examples

   The numerical results shown for this example may differ across
   platforms. The results depend on the SPICE kernels used as
   input, the compiler and supporting libraries, and the machine
   specific arithmetic implementation.

   1) Given a character string, get the n'th word within, and the
      word's location.


      Example code begins here.


      /.
         Program nthwd_ex1
      ./
      #include <stdio.h>
      #include "SpiceUsr.h"

      int main( )
      {

         /.
         Local parameters.
         ./
         #define STRING       " Now is the time,   for all good men     to " \
                              "come."
         #define WRDSZ        6

         /.
         Local variables.
         ./
         SpiceChar            word   [WRDSZ];
         SpiceInt             loc;
         SpiceInt             nth;

         for ( nth = -1; nth <= 11; nth++ )
         {
            nthwd_c ( STRING, nth-1, WRDSZ, word, &loc );
            printf( "Word # %2d  is <%s>, starting at position %2d\n",
                                             (int)nth, word, (int)loc );
         }

         return ( 0 );
      }


      When this program was executed on a Mac/Intel/cc/64-bit
      platform, the output was:


      Word # -1  is <>, starting at position -1
      Word #  0  is <>, starting at position -1
      Word #  1  is <Now>, starting at position  1
      Word #  2  is <is>, starting at position  5
      Word #  3  is <the>, starting at position  8
      Word #  4  is <time,>, starting at position 12
      Word #  5  is <for>, starting at position 20
      Word #  6  is <all>, starting at position 24
      Word #  7  is <good>, starting at position 28
      Word #  8  is <men>, starting at position 33
      Word #  9  is <to>, starting at position 41
      Word # 10  is <come.>, starting at position 44
      Word # 11  is <>, starting at position -1

Restrictions

   None.

Literature_References

   None.

Author_and_Institution

   J. Diaz del Rio     (ODC Space)

Version

   -CSPICE Version 1.0.0, 01-NOV-2021 (JDR)

Index_Entries

   n'th word in a character_string