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.\"     @(#)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)
.\"
.TH STRTOD 3 "March 4th, 1996" "BSD Manual Page" "Library functions"
.SH NAME
strtod \- convert ASCII string to double
.SH SYNOPSIS
.B #include <stdlib.h>
.sp
.BI "double strtod(const char *" nptr ", char **" endptr );
.SH DESCRIPTION
The
.B strtod()
function converts the initial portion of the string pointed to by
.I nptr
to
.B double
representation.

The expected form of the string is optional leading white space as
checked by \fIisspace\fP(3), an optional plus (``+'') or minus sign
(``-'') followed by a sequence of digits optionally containing a
decimal-point character, optionally followed by an exponent.  An
exponent consists of an ``E'' or ``e'', followed by an optional plus or
minus sign, followed by a non-empty sequence of digits.  If the locale
is not "C" or "POSIX", different formats may be used.
.SH "RETURN VALUES"
The
.B strtod
function returns 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
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
.SH "SEE ALSO"
.BR atof (3),
.BR atoi (3),
.BR atol (3),
.BR strtol (3),
.BR strtoul (3)