WCSTOD(3)

NAME
wcstod, wcstof, _wcstod_r, _wcstof_r - wide char string to double or float

SYNOPSIS

#include <stdlib.h>

double wcstod(const wchar_t *__restrict str, wchar_t **__restrict tail);

float wcstof(const wchar_t *__restrict str, wchar_t **__restrict tail);

double _wcstod_r(void *reent, const wchar_t *str, wchar_t **tail);

float _wcstof_r(void *reent, const wchar_t *str, wchar_t **tail);

DESCRIPTION

The function wcstod parses the wide character string str, producing a substring which can be converted to a double value. The substring converted is the longest initial subsequence of str, beginning with the first non-whitespace character, that has one of these formats:

    [+|-]digits[.[digits]][(e|E)[+|-]digits]
    [+|-].digits[(e|E)[+|-]digits]
    [+|-](i|I)(n|N)(f|F)[(i|I)(n|N)(i|I)(t|T)(y|Y)]
    [+|-](n|N)(a|A)(n|N)[<(>[hexdigits]<)>]
    [+|-]0(x|X)hexdigits[.[hexdigits]][(p|P)[+|-]digits]
    [+|-]0(x|X).hexdigits[(p|P)[+|-]digits]

The substring contains no characters if str is empty, consists entirely of whitespace, or if the first non-whitespace character is something other than +, -, ., or a digit, and cannot be parsed as infinity or NaN. If the platform does not support NaN, then NaN is treated as an empty substring. If the substring is empty, no conversion is done, and the value of str is stored in *tail. Otherwise, the substring is converted, and a pointer to the final string (which will contain at least the terminating null character of str) is stored in *tail. If you want no assignment to *tail, pass a null pointer as tail. wcstof is identical to wcstod except for its return type.

This implementation returns the nearest machine number to the input decimal string. Ties are broken by using the IEEE round-even rule. However, wcstof is currently subject to double rounding errors.

The alternate functions _wcstod_r and _wcstof_r are reentrant versions of wcstod and wcstof, respectively. The extra argument reent is a pointer to a reentrancy structure.

RETURNS

Return the converted substring value, if any. If no conversion could be performed, 0 is returned. If the correct value is out of the range of representable values, plus or minus HUGE_VAL is returned, and ERANGE is stored in errno. If the correct value would cause underflow, 0 is returned and ERANGE is stored in errno.

Supporting OS subroutines required: close, fstat, isatty, lseek, read, sbrk, write.

AUTHORS

Steve Chamberlain
    Author.

Roland Pesch
    Author.

Red Hat Support

Jeff Johnston
    Author.

COPYRIGHT

This file documents the ANSI C library.

Copyright (C) 1992, 1993, 1994-2014 Red Hat, Inc.

libc includes software developed by the University of California, Berkeley and its contributors.

libc includes software developed by Martin Jackson, Graham Haley and Steve Chamberlain of Tadpole Technology and released to Cygnus.

libc uses floating-point conversion software developed at AT&T, which includes this copyright information:

The author of this software is David M. Gay.

Copyright (c) 1991 by AT&T.

Permission to use, copy, modify, and distribute this software for any purpose without fee is hereby granted, provided that this entire notice is included in all copies of any software which is or includes a copy or modification of this software and in all copies of the supporting documentation for such software.

THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, subject to the terms of the GNU General Public License, which includes the provision that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

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