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