185 lines
6.0 KiB
Groff
185 lines
6.0 KiB
Groff
.\" Copyright (c) 1990, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to Berkeley by
|
|
.\" the American National Standards Committee X3, on Information
|
|
.\" Processing Systems.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)strtod.3 8.1 (Berkeley) 6/4/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd March 2, 2003
|
|
.Dt STRTOD 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm strtod , strtof , strtold
|
|
.Nd convert
|
|
.Tn ASCII
|
|
string to floating point
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In stdlib.h
|
|
.Ft double
|
|
.Fn strtod "const char * restrict nptr" "char ** restrict endptr"
|
|
.Ft float
|
|
.Fn strtof "const char * restrict nptr" "char ** restrict endptr"
|
|
.Ft long double
|
|
.Fn strtold "const char * restrict nptr" "char ** restrict endptr"
|
|
.Sh DESCRIPTION
|
|
These conversion
|
|
functions convert the initial portion of the string
|
|
pointed to by
|
|
.Fa nptr
|
|
to
|
|
.Vt double ,
|
|
.Vt float ,
|
|
and
|
|
.Vt long double
|
|
representation, respectively.
|
|
.Pp
|
|
The expected form of the string is an optional plus (``+'') or minus
|
|
sign (``\-'') followed by either:
|
|
.Bl -bullet
|
|
.It
|
|
a decimal significand consisting of a sequence of decimal digits
|
|
optionally containing a decimal-point character, or
|
|
.It
|
|
a hexadecimal significand consisting of a ``0X'' or ``0x'' followed
|
|
by a sequence of hexadecimal digits optionally containing a
|
|
decimal-point character.
|
|
.El
|
|
.Pp
|
|
In both cases, the significand may be optionally followed by an
|
|
exponent.
|
|
An exponent consists of an ``E'' or ``e'' (for decimal
|
|
constants) 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 scaling is instead done by powers
|
|
of 2.
|
|
.Pp
|
|
Alternatively, if the portion of the string following the optional
|
|
plus or minus sign begins with ``INFINITY'' or ``NAN'', ignoring
|
|
case, it is interpreted as an infinity or a quiet NaN, respectively.
|
|
.Pp
|
|
In any of the above cases, leading white-space characters in the
|
|
string (as defined by the
|
|
.Xr isspace 3
|
|
function) are skipped.
|
|
The decimal point
|
|
character is defined in the program's locale (category
|
|
.Dv LC_NUMERIC ) .
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn strtod ,
|
|
.Fn strtof ,
|
|
and
|
|
.Fn strtold
|
|
functions return the converted value, if any.
|
|
.Pp
|
|
If
|
|
.Fa endptr
|
|
is not
|
|
.Dv NULL ,
|
|
a pointer to the character after the last character used
|
|
in the conversion is stored in the location referenced by
|
|
.Fa endptr .
|
|
.Pp
|
|
If no conversion is performed, zero is returned and the value of
|
|
.Fa nptr
|
|
is stored in the location referenced by
|
|
.Fa endptr .
|
|
.Pp
|
|
If the correct value would cause overflow, plus or minus
|
|
.Dv HUGE_VAL ,
|
|
.Dv HUGE_VALF ,
|
|
or
|
|
.Dv HUGE_VALL
|
|
is returned (according to the sign and type of the return value), and
|
|
.Er ERANGE
|
|
is stored in
|
|
.Va errno .
|
|
If the correct value would cause underflow, zero is
|
|
returned and
|
|
.Er ERANGE
|
|
is stored in
|
|
.Va errno .
|
|
.Sh ERRORS
|
|
.Bl -tag -width Er
|
|
.It Bq Er ERANGE
|
|
Overflow or underflow occurred.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr atof 3 ,
|
|
.Xr atoi 3 ,
|
|
.Xr atol 3 ,
|
|
.Xr strtol 3 ,
|
|
.Xr strtoul 3 ,
|
|
.Xr wcstod 3
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn strtod
|
|
function
|
|
conforms to
|
|
.St -isoC-99 ,
|
|
with the exception of the bug noted below.
|
|
.Sh BUGS
|
|
These routines do not recognize the C99 ``NaN(...)'' syntax.
|
|
.Sh AUTHORS
|
|
The author of this software is
|
|
.An David M. Gay .
|
|
.Pp
|
|
Copyright (c) 1998 by Lucent Technologies
|
|
.br
|
|
All Rights Reserved
|
|
.Pp
|
|
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.
|
|
.Pp
|
|
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.
|