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.\" Copyright (c) 1990, 1991 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 5.3 (Berkeley) 6/29/91
.\"
.\" Modified Sun Aug 21 17:16:22 1994 by Rik Faith (faith@cs.unc.edu)
.\" Modified Sat May 04 19:34:31 MET DST 1996 by Michael Haardt
.\" (michael@cantor.informatik.rwth-aachen.de)
.\" Added strof, strold, aeb, 2001-06-07
.\"
.TH STRTOD 3 2001-06-07 "Linux" "Library functions"
.SH NAME
strtod, strtof, strtold \- convert ASCII string to floating point number
.SH SYNOPSIS
.B #include <stdlib.h>
.sp
.BI "double strtod(const char *" nptr ", char **" endptr );
.br
.BI "float strtof(const char *" nptr ", char **" endptr );
.br
.BI "long double strtold(const char *" nptr ", char **" endptr );
.SH DESCRIPTION
The
.BR strtod ,
.BR strtof ,
and
.B strtold
functions convert the initial portion of the string pointed to by
.I nptr
to
.BR double ,
.BR float ,
and
.B long double
representation, respectively.
The expected form of the (initial portion of the) string is
optional leading white space as recognized by \fIis\%space\fP(3),
an optional plus (``+'') or minus sign (``-'') and then either
(i) a decimal number, or (ii) a hexadecimal number,
or (iii) an infinity, or (iv) a NAN (not-a-number).
.LP
A
.I "decimal number"
consists of a nonempty sequence of decimal digits
possibly containing a radix character (decimal point, locale dependent,
usually ``.''), optionally followed by a decimal exponent. A
decimal exponent consists of an ``E'' or ``e'', followed by an
optional plus or minus sign, followed by a non-empty sequence of
decimal digits, and indicates multiplication by a power of 10.
.LP
A
.I "hexadecimal number"
consists of a ``0x'' or ``0X'' followed by a nonempty sequence of
hexadecimal digits possibly containing a radix character,
optionally followed by a binary exponent. A binary exponent
consists of a ``P'' or ``p'', followed by an optional
plus or minus sign, followed by a non-empty sequence of
decimal digits, and indicates multiplication by a power of 2.
At least one of radix character and binary exponent must be present.
.LP
An
.I infinity
is either ``INF'' or ``INFINITY'', disregarding case.
.LP
A
.I NAN
is ``NAN'' (disregarding case) optionally followed by `(',
a sequence of characters, followed by ')'.
The character string specifies in an implementation-dependent
way the type of NAN.
.SH "RETURN VALUE"
These functions return the converted value, if any.
If
.I endptr
is not
.BR NULL ,
a pointer to the character after the last character used in the conversion
is stored in the location referenced by
.IR endptr .
If no conversion is performed, zero is returned and the value of
.I nptr
is stored in the location referenced by
.IR endptr .
If the correct value would cause overflow, plus or minus
.B HUGE_VAL
.RB ( HUGE_VALF ,
.BR HUGE_VALL )
is returned (according to the sign of the value), and
.B ERANGE
is stored in
.IR errno .
If the correct value would cause underflow, zero is
returned and
.B ERANGE
is stored in
.IR errno .
.SH ERRORS
.TP
.B ERANGE
Overflow or underflow occurred.
.SH "CONFORMING TO"
ANSI C describes
.BR strtod ,
C99
describes the other two functions.
.SH "SEE ALSO"
.BR atof (3),
.BR atoi (3),
.BR atol (3),
.BR strtol (3),
.BR strtoul (3)
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