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32 .\" @(#)strtod.3 8.1 (Berkeley) 6/4/93
33 .\" $FreeBSD: src/lib/libc/stdlib/strtod.3,v 1.21 2007/01/09 00:28:10 imp Exp $
34 .\" $DragonFly: src/lib/libc/stdlib/strtod.3,v 1.2 2003/06/17 04:26:46 dillon Exp $
45 string to floating point
51 .Fn strtod "const char * restrict nptr" "char ** restrict endptr"
53 .Fn strtof "const char * restrict nptr" "char ** restrict endptr"
55 .Fn strtold "const char * restrict nptr" "char ** restrict endptr"
58 functions convert the initial portion of the string
66 representation, respectively.
68 The expected form of the string is an optional plus (``+'') or minus
69 sign (``\-'') followed by either:
72 a decimal significand consisting of a sequence of decimal digits
73 optionally containing a decimal-point character, or
75 a hexadecimal significand consisting of a ``0X'' or ``0x'' followed
76 by a sequence of hexadecimal digits optionally containing a
77 decimal-point character.
80 In both cases, the significand may be optionally followed by an
82 An exponent consists of an ``E'' or ``e'' (for decimal
83 constants) or a ``P'' or ``p'' (for hexadecimal constants),
84 followed by an optional plus or minus sign, followed by a
85 sequence of decimal digits.
86 For decimal constants, the exponent indicates the power of 10 by
87 which the significand should be scaled.
88 For hexadecimal constants, the scaling is instead done by powers
91 Alternatively, if the portion of the string following the optional
92 plus or minus sign begins with ``INFINITY'' or ``NAN'', ignoring
93 case, it is interpreted as an infinity or a quiet NaN, respectively.
95 In any of the above cases, leading white-space characters in the
96 string (as defined by the
98 function) are skipped.
100 character is defined in the program's locale (category
108 functions return the converted value, if any.
114 a pointer to the character after the last character used
115 in the conversion is stored in the location referenced by
118 If no conversion is performed, zero is returned and the value of
120 is stored in the location referenced by
123 If the correct value would cause overflow, plus or minus
128 is returned (according to the sign and type of the return value), and
132 If the correct value would cause underflow, zero is
140 Overflow or underflow occurred.
155 with the exception of the bug noted below.
157 The author of this software is
160 Copyright (c) 1998 by Lucent Technologies
163 Permission to use, copy, modify, and distribute this software and
164 its documentation for any purpose and without fee is hereby
165 granted, provided that the above copyright notice appear in all
166 copies and that both that the copyright notice and this
167 permission notice and warranty disclaimer appear in supporting
168 documentation, and that the name of Lucent or any of its entities
169 not be used in advertising or publicity pertaining to
170 distribution of the software without specific, written prior
173 LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
174 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
175 IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
176 SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
177 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
178 IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
179 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
183 These routines do not recognize the C99 ``NaN(...)'' syntax.