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.Dd April 1, 2020 33.Dt ATOF 3 34.Os 35.Sh NAME 36.Nm atof 37.Nd convert 38.Tn ASCII 39string to double 40.Sh LIBRARY 41.Lb libc 42.Sh SYNOPSIS 43.In stdlib.h 44.Ft double 45.Fn atof "const char *nptr" 46.Sh DESCRIPTION 47The 48.Fn atof 49function converts the initial portion of the string pointed to by 50.Fa nptr 51to 52.Vt double 53representation. 54.Pp 55It is equivalent to: 56.Bd -literal -offset indent 57strtod(nptr, (char **)NULL); 58.Ed 59.Pp 60The decimal point 61character is defined in the program's locale (category 62.Dv LC_NUMERIC ) . 63.Sh IMPLEMENTATION NOTES 64The 65.Fn atof 66function is not thread-safe and also not async-cancel-safe. 67.Pp 68The 69.Fn atof 70function has been deprecated by 71.Fn strtod 72and should not be used in new code. 73.Sh ERRORS 74The function 75.Fn atof 76need not affect the value of 77.Va errno 78on an error. 79.Sh SEE ALSO 80.Xr atoi 3 , 81.Xr atol 3 , 82.Xr strtod 3 , 83.Xr strtol 3 , 84.Xr strtoul 3 85.Sh STANDARDS 86The 87.Fn atof 88function conforms to 89.St -p1003.1-90 , 90.St -isoC , 91and 92.St -isoC-99 . 93.Sh HISTORY 94The 95.Fn atof 96function appeared in 97.At v1 . 98