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STRTOD(3)		    Library Functions Manual		     STRTOD(3)

NAME
       strtod, strtof, strtold -- convert ASCII	string to floating point

LIBRARY
       Standard	C Library (libc, -lc)

SYNOPSIS
       #include	<stdlib.h>

       double
       strtod(const char * restrict nptr, char ** restrict endptr);

       float
       strtof(const char * restrict nptr, char ** restrict endptr);

       long double
       strtold(const char * restrict nptr, char	** restrict endptr);

DESCRIPTION
       These  conversion  functions  convert the initial portion of the	string
       pointed to by nptr to double, float, and	 long  double  representation,
       respectively.

       The  expected  form  of the string is an	optional plus (``+'') or minus
       sign (``-'') followed by	either:

       •   a decimal significand consisting of a sequence  of  decimal	digits
	   optionally containing a decimal-point character, or

       •   a hexadecimal significand consisting	of a ``0X'' or ``0x'' followed
	   by  a  sequence of hexadecimal digits optionally containing a deci-
	   mal-point character.

       In both cases, the significand may be optionally	followed by  an	 expo-
       nent.   An  exponent  consists  of  an ``E'' or ``e'' (for decimal con-
       stants) or a ``P'' or ``p'' (for	hexadecimal constants),	followed by an
       optional	plus or	minus sign, followed by	a sequence of decimal  digits.
       For  decimal constants, the exponent indicates the power	of 10 by which
       the significand should be scaled.  For hexadecimal constants, the scal-
       ing is instead done by powers of	2.

       Alternatively, if the portion of	the string following the optional plus
       or minus	sign begins with "INFINITY" or "NAN", ignoring case, it	is in-
       terpreted as an infinity	or a  quiet  NaN,  respectively.   The	syntax
       "NAN(s)", where s is an alphanumeric string, produces the same value as
       the call	nan("s") (respectively,	nanf("s") and nanl("s").)

       In any of the above cases, leading white-space characters in the	string
       (as defined by the isspace(3) function) are skipped.  The decimal point
       character is defined in the program's locale (category LC_NUMERIC).

RETURN VALUES
       The  strtod(),  strtof(),  and strtold()	functions return the converted
       value, if any.

       If endptr is not	NULL, a	pointer	to the character after the last	 char-
       acter  used  in	the conversion is stored in the	location referenced by
       endptr.

       If no conversion	is performed, zero is returned and the value  of  nptr
       is stored in the	location referenced by endptr.

       If  the	correct	 value	would  cause overflow, plus or minus HUGE_VAL,
       HUGE_VALF, or HUGE_VALL is returned (according to the sign and type  of
       the return value), and ERANGE is	stored in errno.  If the correct value
       would cause underflow, zero is returned and ERANGE is stored in errno.

ERRORS
       [ERANGE]		  Overflow or underflow	occurred.

SEE ALSO
       atof(3),	atoi(3), atol(3), nan(3), strtol(3), strtoul(3), wcstod(3)

STANDARDS
       The strtod() function conforms to ISO/IEC 9899:1999 ("ISO C99").

AUTHORS
       The author of this software is David M. Gay.

       Copyright (c) 1998 by Lucent Technologies
       All Rights Reserved

       Permission to use, copy,	modify,	and distribute this software and
       its documentation for any purpose and without fee is hereby
       granted,	provided that the above	copyright notice appear	in all
       copies and that both that the copyright notice and this
       permission notice and warranty disclaimer appear	in supporting
       documentation, and that the name	of Lucent or any of its	entities
       not be used in advertising or publicity pertaining to
       distribution of the software without specific, written prior
       permission.

       LUCENT DISCLAIMS	ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
       INCLUDING ALL IMPLIED WARRANTIES	OF MERCHANTABILITY AND FITNESS.
       IN NO EVENT SHALL LUCENT	OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
       SPECIAL,	INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
       WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
       IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
       ARISING OUT OF OR IN CONNECTION WITH THE	USE OR PERFORMANCE OF
       THIS SOFTWARE.

FreeBSD	15.0			 May 11, 2010			     STRTOD(3)

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