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.\" $FreeBSD$ 34.\" 35.Dd April 1, 2020 36.Dt ATOF 3 37.Os 38.Sh NAME 39.Nm atof 40.Nd convert 41.Tn ASCII 42string to double 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.In stdlib.h 47.Ft double 48.Fn atof "const char *nptr" 49.Sh DESCRIPTION 50The 51.Fn atof 52function converts the initial portion of the string pointed to by 53.Fa nptr 54to 55.Vt double 56representation. 57.Pp 58It is equivalent to: 59.Bd -literal -offset indent 60strtod(nptr, (char **)NULL); 61.Ed 62.Pp 63The decimal point 64character is defined in the program's locale (category 65.Dv LC_NUMERIC ) . 66.Sh IMPLEMENTATION NOTES 67The 68.Fn atof 69function is not thread-safe and also not async-cancel-safe. 70.Pp 71The 72.Fn atof 73function has been deprecated by 74.Fn strtod 75and should not be used in new code. 76.Sh ERRORS 77The function 78.Fn atof 79need not affect the value of 80.Va errno 81on an error. 82.Sh SEE ALSO 83.Xr atoi 3 , 84.Xr atol 3 , 85.Xr strtod 3 , 86.Xr strtol 3 , 87.Xr strtoul 3 88.Sh STANDARDS 89The 90.Fn atof 91function conforms to 92.St -p1003.1-90 , 93.St -isoC , 94and 95.St -isoC-99 . 96.Sh HISTORY 97The 98.Fn atof 99function appeared in 100.At v1 . 101