watof(3C)

NAME

     wcstod, wstod, watof -  convert  wide  character  string  to
     double-precision number

SYNOPSIS

     #include <wchar.h>

     double wcstod(const wchar_t *nptr, wchar_t **endptr);

     double wstod(const wchar_t *nptr, wchar_t **endptr);

     double watof(wchar_t *nptr);

DESCRIPTION

     The wcstod() and wstod() functions convert the initial  por-
     tion of the wide character string pointed to by nptr to dou-
     ble representation. They  first  decompose  the  input  wide
     character  string  into  three  parts:  an initial, possibly
     empty, sequence of  white-space  wide  character  codes  (as
     specified  by  iswspace(3C)); a subject sequence interpreted
     as a floating-point constant;  and  a  final  wide-character
     string  of  one  or  more unrecognised wide-character codes,
     including the terminating null wide character  code  of  the
     input  wide  character  string. They then attempt to convert
     the subject sequence to a floating-point number, and  return
     the result.

     The expected form of the subject sequence is an optional `+'
     or  `-' sign, then a non-empty sequence of digits optionally
     containing a radix,  then  an  optional  exponent  part.  An
     exponent  part  consists  of  `e'  or  `E',  followed  by an
     optional sign, followed by one or more decimal  digits.  The
     subject  sequence  is  defined as the longest initial subse-
     quence of the input wide character string, starting with the
     first  non-white-space  wide-character  code, that is of the
     expected  form.  The  subject  sequence  contains  no  wide-
     character  codes if the input wide character string is empty
     or consists entirely of white-space wide-character codes, or
     if  the  first  wide-character  code that is not white space
     other than a sign, a digit or a radix.

     If the subject sequence has the expected form, the  sequence
     of wide-character codes starting with the first digit or the
     radix (whichever occurs first) is interpreted as a  floating
     constant as defined in the C language, except that the radix
     is used in place  of  a  period,  and  that  if  neither  an
     exponent  part  nor  a  radix appears, a radix is assumed to
     follow the last digit in the wide character string.  If  the
     subject  sequence  begins  with  a minus sign (-), the value
     resulting from the conversion is negated. A pointer  to  the
     final wide character string is stored in the  object pointed
     to by endptr, provided that  endptr is not a null pointer.
     The radix is  defined  in  the  program's  locale  (category
     LC_NUMERIC).  In  the POSIX locale, or in a locale where the
     radix is not defined, the radix defaults to a period (.).

     In  other  than  the  POSIX  locale,  other  implementation-
     dependent subject sequence forms may be accepted.

     If the subject sequence  is  empty  or  does  not  have  the
     expected  form,  no  conversion  is  performed; the value of
     nptr is stored in the object pointed to by endptr,  provided
     that  endptr is not a null pointer.

     The watof(str) function is equivalent to wstod(str, (wchar_t
     **)NULL).

RETURN VALUES

     The wcstod() and  wstod()  functions  return  the  converted
     value,  if  any.  If  no conversion could be performed, 0 is
     returned and errno may be set to EINVAL.

     If the correct value is outside the range  of  representable
     values,  _HUGE_VAL is returned (according to the sign of the
     value), and errno is set to ERANGE.

     If the correct value would cause underflow, 0  is  returned,
     and  errno is set to ERANGE.

ERRORS

     The wcstod() and wstod() functions will fail if:

     ERANGE
           The value to  be  returned  would  cause  overflow  or
           underflow.

     The wcstod() and wcstod() functions may fail if:

     EINVAL
           No conversion could be performed.

USAGE

     Because 0 is returned on error and is also a valid return on
     success,  an  application  wishing to check for error situa-
     tions should set errno to 0 call wcstod() or  wstod(),  then
     check   errno  and  if  it  is non-zero, assume an error has
     occurred.

ATTRIBUTES

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

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

SEE ALSO

     iswspace(3C),  localeconv(3C),   scanf(3C),   setlocale(3C),
     wcstol(3C), attributes(5)