1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)atof.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/stdlib/atof.3,v 1.17 2007/01/09 00:28:09 imp Exp $ 34.\" 35.Dd November 17, 2013 36.Dt ATOF 3 37.Os 38.Sh NAME 39.Nm atof , 40.Nm atof_l 41.Nd convert 42.Tn ASCII 43string to double 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In stdlib.h 48.Ft double 49.Fn atof "const char *nptr" 50.In xlocale.h 51.Ft double 52.Fn atof_l "const char *nptr" "locale_t loc" 53.Sh DESCRIPTION 54The 55.Fn atof 56function converts the initial portion of the string pointed to by 57.Fa nptr 58to 59.Vt double 60representation. 61.Pp 62It is equivalent to: 63.Bd -literal -offset indent 64strtod(nptr, NULL); 65.Ed 66.Pp 67The decimal point 68character is defined in the program's locale (category 69.Dv LC_NUMERIC ) . 70.Pp 71The _l-suffixed version takes an explicit locale argument, whereas the 72non-suffixed version use the current global or per-thread locale. 73.Sh IMPLEMENTATION NOTES 74The 75.Fn atof 76function is not thread-safe and also not async-cancel-safe. 77.Pp 78The 79.Fn atof 80function has been deprecated by 81.Fn strtod 82and should not be used in new code. 83.Sh ERRORS 84The function 85.Fn atof 86need not affect the value of 87.Va errno 88on an error. 89.Sh SEE ALSO 90.Xr atoi 3 , 91.Xr atol 3 , 92.Xr strtod 3 , 93.Xr strtol 3 , 94.Xr strtoul 3 , 95.Xr xlocale 3 96.Sh STANDARDS 97The 98.Fn atof 99function conforms to 100.St -p1003.1-90 , 101.St -isoC , 102and 103.St -isoC-99 . 104