.\" Copyright (c) 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.
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.\" 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.
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.\"     @(#)atof.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/stdlib/atof.3,v 1.17 2007/01/09 00:28:09 imp Exp $
.\"
.Dd June 4, 1993
.Dt ATOF 3
.Os
.Sh NAME
.Nm atof
.Nd convert
.Tn ASCII
string to double
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft double
.Fn atof "const char *nptr"
.Sh DESCRIPTION
The
.Fn atof
function converts the initial portion of the string pointed to by
.Fa nptr
to
.Vt double
representation.
.Pp
It is equivalent to:
.Bd -literal -offset indent
strtod(nptr, (char **)NULL);
.Ed
.Pp
The decimal point
character is defined in the program's locale (category
.Dv LC_NUMERIC ) .
.Sh IMPLEMENTATION NOTES
The
.Fn atof
function is not thread-safe and also not async-cancel-safe.
.Pp
The
.Fn atof
function has been deprecated by
.Fn strtod
and should not be used in new code.
.Sh ERRORS
The function
.Fn atof
need not affect the value of
.Va errno
on an error.
.Sh SEE ALSO
.Xr atoi 3 ,
.Xr atol 3 ,
.Xr strtod 3 ,
.Xr strtol 3 ,
.Xr strtoul 3
.Sh STANDARDS
The
.Fn atof
function conforms to
.St -p1003.1-90 ,
.St -isoC ,
and
.St -isoC-99 .