Procedure

   lx4num_c (Scan for number) 

   void lx4num_c ( ConstSpiceChar   * string,
                   SpiceInt           first,
                   SpiceInt         * last,
                   SpiceInt         * nchar  )

Abstract

   Scan a string from a specified starting position for the
   end of a number.

Required_Reading

   None.

Keywords

   PARSING

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   string     I   Any character string.
   first      I   First character to scan from in string.
   last       O   Last character that is part of a number.
   nchar      O   Number of characters in the number.

Detailed_Input

   string      is any character string.

   first       is the location in the string to beginning scanning
               for a number. It is assumed that the
               number begins at first.

               The normal range of first is 0 : strlen(string)-1.

Detailed_Output

   last        is the last character at or after first such that the
               substring ranging from string[first] through
               string[last] is a number. If there is no such
               substring, last will be returned with the value first-1.

               If a number is found, last will be in the
               range is 0 : strlen(string)-1.


   nchar       is the number of characters in the number that
               begins at index first and ends at last. If there is no
               such string nchar will be given the value 0.

Parameters

   None.

Exceptions

   1)  If `first' is beyond either end of the string, then `last' will be
       returned with the value first-1 and `nchar' will be returned
       with the value 0.

   2)  If string[first] is not part of a number then `last' will be
       returned with the value first-1 and `nchar' will be returned with
       the value 0.

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

   4)  If the input string has length zero, `last' will be set to first-1
       and `nchar' will be set to zero. This case is not considered an
       error.

Files

   None.

Particulars

   This routine allows you to scan forward in a string to locate a
   number that begins on the input character first. Note that all
   decimal numbers are included in the list of numbers. The main
   difference between decimal numbers and numbers is that numbers may
   have an exponential expression attached (i.e. the exponent character
   'e','E','d' or 'D' followed by an signed integer).

Examples

   1) Suppose you believe that a string has the form

         X%Y%Z

      where X, Y, and Z are numbers of some unknown length and
      % stands for any character that cannot occur in a number.
      You could use this routine to locate the numbers in the
      string as shown below. We'll keep track of the beginning and
      ending of the numbers in the integer arrays b and e.


         #include <string.h>
         #include "SpiceUsr.h"

               .
               .
               .

         first = 0;
         i     = 0;
         len   = strlen(string);

         while ( first < len-1 )
         {
            lx4num_c ( string, first, &last, &nchar );

            if ( nchar > 0 )
            {
               i++;

               b[i]  = first;
               e[i]  = last;
               first = last  +  2;
            }
            else
            {
               first++;
            }
         }

Restrictions

   None.

Literature_References

   None.

Author_and_Institution

   N.J. Bachman        (JPL)
   J. Diaz del Rio     (ODC Space)
   W.L. Taber          (JPL)

Version

   -CSPICE Version 1.0.1, 04-AUG-2021 (JDR)

       Edited the header to comply with NAIF standard.

   -CSPICE Version 1.0.0, 18-AUG-2002 (NJB) (WLT)

Index_Entries

   Scan a string for a number.