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wcstold(3)
NAME
  wcstold - Convert a wide-character string to a long double-precision value

SYNOPSIS
  #include <wchar.h>

  long double wcstold(
	  const wchar_t *ws,
	  wchar_t **endptr );

LIBRARY
  Standard C Library (libc)

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  wcstold(): ISO C

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  ws  Points to the wide-character string to be converted to a long double-
      precision floating-point value.

  endptr
      Points to a pointer in which the wcstold() function stores the position
      of the final wide-character segment of the string, which contains
      unrecognized characters and the null terminator.

DESCRIPTION
  The wcstold() function converts the initial portion of the wide-character
  string pointed to by the ws parameter to a long double-precision floating-
  point value. The input wide-character string is first broken down into
  three parts: an initial (possibly empty) sequence of white-space wide-
  character codes (as specified by the iswspace() function); a subject
  sequence interpreted as a floating-point constant; and a final wide-
  character string of one or more unrecognized wide-character codes,
  including the terminating null wide character. The subject sequence is then
  (if possible) converted to a floating-point number and returned as the
  result of the wcstold() function.

  The subject sequence is expected to consist of an optional + (plus sign) or
  - (minus sign), a nonempty sequence of digits (which may contain a radix
  character), and an optional exponent. The exponent consists of e or E,
  followed by an optional sign, followed by one or more decimal digits. The
  subject sequence is the longest initial subsequence of the input wide-
  character string (starting with the first nonwhite-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 nonwhite-
  space wide-character code is other than a sign, a digit, or a radix
  character.

  If the subject sequence is valid, the sequence of wide-character codes,
  starting with the first digit or radix character (whichever occurs first),
  is interpreted as a floating-point or double-precision floating-point
  constant.  The locale's radix character is treated as equivalent to the .
  (period) within floating-point constants in the C locale. If neither an
  exponent or radix character appears, a radix character is assumed to follow
  the last digit in the wide-character string. If the subject sequence begins
  with - ( a minus sign), the conversion value is negated. The radix
  character is determined by the LC_NUMERIC category in the program's current
  locale.  In the C locale, or in a locale where the radix character is not
  defined, the radix character is a . (period).

  The wcstold() function stores a pointer to the final wide-character segment
  of the string (starting with the first invalid character) in the object
  pointed to by the endptr parameter, unless the endptr parameter is a null
  pointer.

RETURN VALUES
  The wcstold() function returns the converted value of a long double-
  precision floating-point value if a valid floating-point constant is found.
  If the converted value is outside the range of representable values (either
  too high or too low), the function returns plus or minus HUGE_VAL and sets
  errno to [ERANGE]. If the converted value would cause underflow, the
  function returns 0 (zero) and sets errno to [ERANGE]. If the subject
  sequence is empty or does not have the expected form, the function performs
  no conversion and returns 0 (zero).  In this case, the value specified by
  the ws parameter is stored in the object pointed to by the endptr
  parameter, provided that the endptr parameter is not a null pointer.

  Since the wcstold() function returns 0 (zero) or HUGE_VAL in the event of
  an error and these values are also valid returns if the wcstold() function
  is successful, applications should set errno to 0 (zero) before each call
  to the wcstold() function and check errno after each return from the
  function. If errno is nonzero after a return, an error occurred.
  Additionally, if 0 (zero) is returned, applications should check if the
  endptr parameter equals the nptr parameter. In this case, there was no
  valid subject string.

ERRORS
  If the following condition occurs, the wcstold() function sets errno to the
  corresponding value:

  [ERANGE]
      The converted value would cause underflow or, if outside the range of
      representable values, overflow.

SEE ALSO
  Functions: atof(3), iswspace(3), localeconv(3), scanf(3), setlocale(3),
  wcstod(3), wcstol(3)

  Standards: standards(5)

Index for Section 3

Alphabetical listing for W

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