WCSTOD(3C) | Standard C Library Functions | WCSTOD(3C) |

#include <wchar.h>doublewcstod(const wchar_t *restrictnptr,wchar_t **restrictendptr);

floatwcstof(const wchar_t *restrictnptr,wchar_t **restrictendptr);

long doublewcstold(const wchar_t *restrictnptr,wchar_t **restrictendptr);

doublewstod(const wchar_t *nptr,wchar_t **endptr);

doublewatof(wchar_t *nptr);

- 1.
- An initial, possibly empty, sequence of white-space wide-character codes
(as specified by
**iswspace**(3C))

- 2.
- A subject sequence interpreted as a floating-point constant or representing infinity or NaN

- 3.
- A final wide-character string of one or more unrecognized wide-character codes, including the terminating null wide-character code of the input wide-character string.

Then they 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 plus or minus sign, then one of the following:

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

- o
- A 0x or 0X, then a non-empty sequence of hexadecimal digits optionally containing a radix character, then an optional binary exponent part

- o
- One of INF or INFINITY, or any other wide string equivalent except for case

- o
- One of NAN or NAN(
*n-wchar-sequence*(*opt*)), or any other wide string ignoring case in the NAN part, where:

n-wchar-sequence: digit nondigit n-wchar-sequence digit n-wchar-sequence nondigit

In default mode for **wcstod()**, only decimal, INF/INFINITY,
and NAN/NAN(*n-wchar-sequence*) forms are recognized. In C99/SUSv3
mode, hexadecimal strings are also recognized.

In default mode for **wcstod()**, the *n-wchar-sequence*
in the NAN(*n-wchar-sequence*) form can contain any character except
')' (right parenthesis) or '\0' (null). In C99/SUSv3 mode, the
*n-wchar-sequence* can contain only upper and lower case letters,
digits, and '_' (underscore).

The **wcstof()** and **wcstold()** functions always function
in C99/SUSv3-conformant mode.

The subject sequence is defined as the longest initial subsequence of the input wide string, starting with the first non-white-space wide character, that is of the expected form. The subject sequence contains no wide characters if the input wide string is not of the expected form.

If the subject sequence has the expected form for a floating-point
number, the sequence of wide characters starting with the first digit or the
radix character (whichever occurs first) is interpreted as a floating
constant according to the rules of the C language, except that the radix
character is used in place of a period, and that if neither an exponent part
nor a radix character appears in a decimal floating-point number, or if a
binary exponent part does not appear in a hexadecimal floating-point number,
an exponent part of the appropriate type with value zero is assumed to
follow the last digit in the string. If the subject sequence begins with a
minus sign, the sequence is interpreted as negated. A wide-character
sequence INF or INFINITY is interpreted as an infinity. A wide-character
sequence NAN or NAN(*n-wchar-sequence*(*opt*)) is interpreted as a
quiet NaN. A pointer to the final wide string is stored in the object
pointed to by *endptr*, provided that *endptr* is not a null
pointer.

If the subject sequence has either the decimal or hexadecimal form, the value resulting from the conversion is rounded correctly according to the prevailing floating point rounding direction mode. The conversion also raises floating point inexact, underflow, or overflow exceptions as appropriate.

The radix character is defined in the program's locale (category
**LC_NUMERIC**). In the POSIX locale, or in a locale where the radix
character is not defined, the radix character defaults to a period
('.').

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 **wcstod()** function does not change the setting of
**errno** if successful.

The **wstod()** function is identical to **wcstod()**.

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

If the correct value is outside the range of representable values,
**±HUGE_VAL**, **±HUGE_VALF**, or
**±HUGE_VALL** is returned (according to the sign of the value), a
floating point overflow exception is raised, and **errno** is set to
**ERANGE**.

If the correct value would cause an underflow, the correctly
rounded result (which may be normal, subnormal, or zero) is returned, a
floating point underflow exception is raised, and **errno** is set to
**ERANGE**.

**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.

ATTRIBUTE TYPE | ATTRIBUTE VALUE |

Interface Stability | wcstod(), wcstof(), and wcstold() are
Standard. |

MT-Level | MT-Safe |

August 25, 2019 |