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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 November 17, 2013
.Dt ATOF 3
.Os
.Sh NAME
.Nm atof ,
.Nm atof_l
.Nd convert
.Tn ASCII
string to double
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft double
.Fn atof "const char *nptr"
.In xlocale.h
.Ft double
.Fn atof_l "const char *nptr" "locale_t loc"
.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, NULL);
.Ed
.Pp
The decimal point
character is defined in the program's locale (category
.Dv LC_NUMERIC ) .
.Pp
The _l-suffixed version takes an explicit locale argument, whereas the
non-suffixed version use the current global or per-thread locale.
.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 ,
.Xr xlocale 3
.Sh STANDARDS
The
.Fn atof
function conforms to
.St -p1003.1-90 ,
.St -isoC ,
and
.St -isoC-99 .