func_to_decimal(3C)

NAME

     string_to_decimal, file_to_decimal, func_to_decimal -  parse
     characters into decimal record

SYNOPSIS

     #include <floatingpoint.h>

     void   string_to_decimal(char   **pc,    int    nmax,    int
     fortran_conventions,      decimal_record      *pd,      enum
     decimal_string_form *pform, char **pechar);

     void    func_to_decimal(char    **pc,    int    nmax,    int
     fortran_conventions,      decimal_record      *pd,      enum
     decimal_string_form    *pform,    char     **pechar,     int
     (*pget)(void), int *pnread, int (*punget)(int c));

     #include <stdio.h>

     void    file_to_decimal(char    **pc,    int    nmax,    int
     fortran_conventions,      decimal_record      *pd,      enum
     decimal_string_form *pform, char  **pechar,  FILE  *pf,  int
     *pnread);

DESCRIPTION

     The char_to_decimal functions parse a numeric token from  at
     most  nmax  characters in a string **pc or file *pf or func-
     tion (*pget)() into a decimal record  *pd,  classifying  the
     form  of the string in *pform and *pechar. The accepted syn-
     tax is intended to be sufficiently flexible  to  accommodate
     many   languages:   whitespace   value  or  whitespace  sign
     value,where whitespace is any number of  characters  defined
     by  isspace  in <ctype.h>, sign is either of [+-], and value
     can be number, nan, or inf. inf can  be  INF  (inf_form)  or
     INFINITY  (infinity_form) without regard to case. nan can be
     NAN (nan_form)  or  NAN(nstring)   (nanstring_form)  without
     regard to case; nstring is any string of characters not con-
     taining ')' or  NULL;  nstring  is  copied  to  pd->ds  and,
     currently,  not used subsequently. number consists of signi-
     ficand or significand efield where significand must  contain
     one or more digits and may contain one point; possible forms
     are

     digits             (int_form)
     digits.            (intdot_form)
     .digits            (dotfrac_form)
     digits.digits       (intdotfrac_form)

     efield consists of echar digits or echar sign  digits,.where
     echar  is  one  of  [Ee],  and  digits  contains one or more
     digits.

     When fortran_conventions is nonzero, additional input  forms
     are accepted according to various Fortran conventions:

     0     no Fortran conventions

     1     Fortran list-directed input conventions

     2     Fortran formatted  input  conventions,  ignore  blanks
           (BN)

     3     Fortran formatted input conventions, blanks are  zeros
           (BZ)

     When fortran_conventions is nonzero, echar may also  be  one
     of [DdQq], and efield may also have the form

          sign digits.

     When fortran_conventions>=  2,  blanks  may  appear  in  the
     digits  strings  for  the  integer,  fraction,  and exponent
     fields and may appear between echar and  the  exponent  sign
     and    after    the    infinity    and    NaN   forms.    If
     fortran_conventions==  2,  the  blanks  are  ignored.   When
     fortran_conventions==  3,  the  blanks that appear in digits
     strings are interpreted  as  zeros,  and  other  blanks  are
     ignored.

     When  fortran_conventions  is  zero,  the  current  locale's
     decimal  point  character is used as the decimal point; when
     fortran_conventions is nonzero, the period is  used  as  the
     decimal point.

     The form of the accepted decimal string is placed in *pform.
     If  an  efield is recognized, *pechar is set to point to the
     echar.

     On input, *pc points to the beginning of a character  string
     buffer of length >= nmax. On output, *pc points to a charac-
     ter in that buffer, one past the  last  accepted  character.
     string_to_decimal()  gets  its  characters  from the buffer;
     file_to_decimal() gets its characters from *pf  and  records
     them in the buffer, and places a null after the last charac-
     ter read. func_to_decimal() gets its characters from an  int
     function (*pget)().

     The scan continues until no more characters  could  possibly
     fit the acceptable syntax or until nmax characters have been
     scanned.  If the nmax limit is not reached then at least one
     extra  character will usually be scanned that is not part of
     the accepted syntax. file_to_decimal() and func_to_decimal()
     set  *pnread to the number of characters read from the file;
     if greater than nmax, some characters were lost. If no char-
     acters  were  lost,  file_to_decimal() and func_to_decimal()
     attempt to push back, with  ungetc(3C)  or  (*punget)(),  as
     many  as  possible  of the excess characters read, adjusting
     *pnread accordingly. If all unget calls are successful, then
     **pc  will  be  NULL.  No  push  back  will  be attempted if
     (*punget)() is NULL.

     Typical declarations for *pget() and *punget() are:

     int xget(void)
          { ...  }
          int (*pget)(void) = xget;
          int xunget(int c)
          { ... }
     int (*punget)(int) = xunget;

     If no valid number  was  detected,  pd->fpclass  is  set  to
     fp_signaling,  *pc  is  unchanged,  and  *pform  is  set  to
     invalid_form.

     atof(3C) and strtod(3C) use  string_to_decimal().  scanf(3C)
     uses file_to_decimal().

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|

SEE ALSO

     ctype(3C),   localeconv(3C),    scanf(3C),    setlocale(3C),
     strtod(3C), ungetc(3C), attributes(5)