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string_to_decimal(3c)

string_to_decimal(3C)    Standard C Library Functions    string_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
       These functions attempt to parse a numeric  token  from  at  most  nmax
       characters  read  from  a string **pc, a file *pf, or function (*pget).
       They set the decimal record *pd to reflect the value of the numeric to‐
       ken recognized and set *pform and *pechar to indicate its form.


       The accepted forms for the numeric token consist of an initial,  possi‐
       bly  empty,  sequence  of  white-space  characters,  as  defined by is‐
       space(3C), followed by a subject sequence representing a numeric value,
       infinity, or NaN. The subject sequence consists of an optional plus  or
       minus sign followed by one of the following:

           o      a non-empty sequence of decimal digits optionally containing
                  a decimal point character, then an optional exponent part


           o      one of INF or INFINITY, ignoring case


           o      one  of  NAN  or NAN(string), ignoring case in the NAN part;
                  string can be any sequence of characters not containing  ')'
                  (right parenthesis) or '\0' (null).



       The  fortran_conventions  argument provides additional control over the
       set of accepted forms. It must be one of the following values:

       0    no Fortran conventions


       1    Fortran list-directed input conventions


       2    Fortran formatted input conventions, blanks are ignored


       3    Fortran formatted input conventions, blanks are interpreted as ze‐
            roes



       When fortran_conventions is zero, the decimal point  character  is  the
       current  locale's  decimal  point character, and the exponent part con‐
       sists of the letter E or e followed by an optional sign and a non-empty
       string of decimal digits.


       When fortran_conventions is non-zero, the decimal  point  character  is
       "." (period), and the exponent part consists of either a sign or one of
       the  letters  E,  e, D, d, Q, or q followed by an optional sign, then a
       non-empty string of decimal digits.


       When fortran_conventions is 2 or 3, blanks  can  appear  in  the  digit
       strings  for the integer, fraction, and exponent parts, between the ex‐
       ponent delimiter and optional exponent sign, and after an  INF,  INFIN‐
       ITY, NAN, or NAN(string). When fortran_conventions is 2, all blanks are
       ignored. When fortran_conventions is 3, blanks in digit strings are in‐
       terpreted as zeros and other blanks are ignored.


       The  following table summarizes the accepted forms and shows the corre‐
       sponding values to which *pform and pd->fpclass are  set.  Here  digits
       represents  any  string  of decimal digits, "." (period) stands for the
       decimal point character, and exponent represents the exponent  part  as
       defined above. Numbers in brackets refer to the notes following the ta‐
       ble.

       tab();  lw(1.64i)  lw(2.01i)  lw(1.85i)  lw(1.64i)  lw(2.01i) lw(1.85i)
       form*pformpd->fpclass _ all white space [1]whitespace_formfp_zero  dig‐
       itsfixed_int_formfp_normal  [2]  digits.fixed_intdot_formfp_normal  [2]
       .digitsfixed_dotfrac_formfp_normal    [2]    digits.digitsfixed_intdot‐
       frac_formfp_normal  [2]  digits  exponentfloating_int_formfp_normal [2]
       digits.  exponentfloating_intdot_formfp_normal  [2]  .digits  exponent‐
       floating_dotfrac_formfp_normal [2] digits.digits  exponentfloating_int‐
       dotfrac_formfp_normal    [2]    INFinf_formfp_infinity   INFINITYinfin‐
       ity_formfp_infinity                                 NANnan_formfp_quiet
       NAN(string)nanstring_formfp_quiet  none of the aboveinvalid_formfp_sig‐
       naling



       Notes:

           1.     The whitespace_form is accepted  only  when  fortran_conven‐
                  tions is 2 or 3 and is interpreted as zero.


           2.     For  all  numeric  forms, pd->fpclass is set to fp_normal if
                  any non-zero digits appear in the integer or fraction parts,
                  and otherwise pd->fpclass is set to fp_zero.




       If the accepted token has one of the numeric  forms  and  represents  a
       non-zero number x, its significant digits are stored in pd->ds. Leading
       and  trailing  zeroes  and  the  radix  point are omitted. pd->sign and
       pd->exponent are set so that if m is the integer represented by pd->ds,

         −1**(pd->sign) * m * 10**(pd->exponent)



       approximates x to at least 511 significant digits. pd->more is set to 1
       if this approximation is not exact (that is, the  accepted  token  con‐
       tains  additional non-zero digits beyond those copied to pd->ds) and to
       0 otherwise.


       If the accepted token has the NAN(string) form, up  to  511  characters
       from the string part are copied to pd->ds.


       pd->ds  is  always terminated by a null byte, and pd->ndigits is set to
       the length of the string stored in pd->ds.


       On entry, *pc points to the beginning of a character string buffer. The
       string_to_decimal() function reads characters from  this  buffer  until
       either  enough  characters  are read to delimit the accepted token (for
       example, a null character marking the end of the string  is  found)  or
       the limit of nmax characters is reached. The file_to_decimal() function
       reads  characters  from the file *pf and stores them in the buffer. The
       func_to_decimal() function reads characters one at a  time  by  calling
       the  function  (*pget)()  and stores them in the buffer; (*pget)() must
       return integer values in the range −1 to 255, where −1  is  interpreted
       as  EOF  and  0, ..., 255 are interpreted as unsigned char values. Both
       file_to_decimal() and func_to_decimal() read  characters  until  either
       enough  characters  are  read to delimit the accepted token, EOF is en‐
       countered, or the limit of nmax characters is reached. These functions,
       therefore, typically read one or more additional characters beyond  the
       end  of  the accepted token and attempt to push back any excess charac‐
       ters read. Provided that the punget argument is not NULL, func_to_deci‐
       mal() pushes back characters one at a  time  by  calling  (*punget)(c),
       where  c  is  an integer in the range 0 to 255 corresponding to a value
       previously read via (*pget)(). After pushing back as many excess  char‐
       acters  as  possible,  file_to_decimal()  and func_to_decimal() store a
       null byte in the buffer following  the  last  character  read  and  not
       pushed  back  and set *pnread to the number of characters stored in the
       buffer prior to this null byte. Since these functions can  read  up  to
       nmax characters, the buffer must be large enough to hold nmax + 1.


       On  exit,  *pc points to the next character in the buffer past the last
       one that was accepted as part of the numeric token. If no  valid  token
       is  found, *pc is unchanged. If file_to_decimal() and func_to_decimal()
       successfully push back all unused characters, *pc points  to  the  null
       byte  stored  in  the  buffer following the last character read and not
       pushed back.


       If the accepted token contains an exponent  part,  *pechar  is  set  to
       point  to  the  position in the buffer where the first character of the
       exponent field is stored. If the accepted token does not contain an ex‐
       ponent part, *pechar is set to NULL.

USAGE
       If the _IOWRT flag is set in *pf,  file_to_decimal()  reads  characters
       directly  from  the  file  buffer until a null character is found. (The
       _IOWRT flag should only be set when file_to_decimal()  is  called  from
       sscanf(3C).) Otherwise, file_to_decimal() uses getc_unlocked(3C), so it
       is not MT-safe unless the caller holds the stream lock.

ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:

       tab()  box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
       TRIBUTE VALUE _ MT-LevelMT-Safe with exceptions


SEE ALSO
       isspace(3C), ctype(3C), decimal_to_floating(3C), getc_unlocked(3C), lo‐
       caleconv(3C), scanf(3C), setlocale(3C), strtod(3C), ungetc(3C), attrib‐
       utes(7)

Oracle Solaris 11.4               1 Oct 2003             string_to_decimal(3C)
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