wcstod(3C)

NAME

wcstod() — convert wide character string to double-precision number

SYNOPSIS

#include <wchar.h>

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

Remarks:

This function is compliant with the XPG4 Worldwide Portability Interface wide-character formatting functions. It parallels the 8-bit character formatting function defined in strtod(3C).

DESCRIPTION

wcstod() returns, as a double-precision floating-point number, the value represented by the wide character string pointed to by nptr. 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.

wcstod() recognizes wide characters in the following sequence:

1.: An optional string of ``white-space'' wide characters which are ignored,
2.: An optional sign,
3.: A string of digits optionally containing a radix character,
4.: An optional e or E followed by an optional sign or space, followed by an integer.

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.

The definition for this function and the type wchar_t are provided in the <wchar.h> header.

APPLICATION USAGE

wcstod() is thread-safe and async-cancel-safe.

EXTERNAL INFLUENCES

Locale

The LC_NUMERIC category determines the value of the radix character within the currently loaded NLS environment.

The LC_CTYPE category determines how wide character codes are interpreted.

International Code Set Support

Single- and multi-byte 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 (case insensitive) it will return _DNANQ.

AUTHOR

wcstod() was developed by AT&T and HP.

STANDARDS CONFORMANCE

wcstod(): XPG4