NAME
wcstod(), wcstof(), wcstold() — convert a wide character string to a double-precision number
SYNOPSIS
#include <wchar.h>
double wcstod(const wchar_t *__restrict nptr, wchar_t **__restrict endptr);
long double wcstold(const wchar_t *__restrict nptr, wchar_t **__restrict endptr);
Itanium(R)-based Systems Only
float wcstof(const wchar_t *restrict nptr, wchar_t **restrict endptr);
Remarks
These functions are compliant with the UNIX standard
Worldwide Portability Interface wide-character formatting functions.
They parallel the 8-bit character formatting functions defined in
strtod(3C),
strtold(3C)
and
strtof(3C)
respectively.
DESCRIPTION
The
wcstod(),
wcstof(),
and
wcstold()
functions return the value represented by the wide-character string
pointed to by
nptr
as a double-precision floating-point number,
single-precision floating-point number,
and long double-precision number, respectively.
The wide character string is scanned
(leading white-space characters as defined by
iswspace()
in
wctype(3C)
are ignored) up to the first unrecognized character.
If no conversion can take place, zero is returned.
The
wcstod(),
wcstof(),
and
wcstold()
functions recognize wide characters in the following sequence:
- 1.
An optional string of white space wide characters, which are ignored
- 2.
An optional sign followed by one of the following:
A string of digits optionally containing a radix character, then an optional
e
or
E
followed by an optional sign or space, followed by an integer
A 0x or 0X, then a non-empty sequence of hexadecimal digits optionally
containing a radix character, then an optional binary exponent part
One of INF or INFINITY, or any other wide string equivalent except for case
One of NAN or NAN(n-wchar-sequence), or any other wide string ignoring
case in the NAN part, where n-wchar-sequence is:
n-wchar-sequence nondigit
The radix character is determined by the current
NLS
environment (see
setlocale(3C)).
If
setlocale()
has not been called successfully, the default
NLS
environment, "C", is used (see
lang(5)).
The default environment specifies a period (.) as the radix character.
If the value of
endptr
is not
(wchar_t **)NULL,
the variable to which it points is set
to point at the wide character after the last number,
if any, that was recognized.
If no number can be formed,
*endptr
is set to
nptr,
and zero is returned.
EXTERNAL INFLUENCES
Environment Variables
LC_NUMERIC
determines the value of the radix character within the currently loaded
NLS
environment.
LC_CTYPE
determines how wide character codes are interpreted.
International Code Set Support
Single- and multibyte character code sets are supported.
RETURN VALUE
If the correct value would cause overflow,
+HUGE_VAL
or
-HUGE_VAL
is returned (according to the sign of the value), and
errno
is set to
ERANGE.
If the correct value would cause underflow, zero is returned and
errno
is set to
ERANGE.
If
wcstod()
encounters an input wide character string equal to
inf
or
infinity
(both case insensitive) it will return
HUGE_VAL.
If
wcstod()
encounters an input wide character string equal to
nan
or
NAN(n-wchar-sequence)
(both case insensitive) it will return
_DNANQ.
AUTHOR
wcstod()
was developed by AT&T and HP.
wcstof()
and
wcstold()
were developed by HP.
STANDARDS CONFORMANCE
wcstod(): XPG4
Printable version
