1.\" Copyright (c) 1990, 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.\" $OpenBSD: atoi.3,v 1.11 2013/07/17 05:42:11 schwarze Exp $ 33.\" 34.Dd $Mdocdate: July 17 2013 $ 35.Dt ATOI 3 36.Os 37.Sh NAME 38.Nm atoi 39.Nd convert 40.Tn ASCII 41string to integer 42.Sh SYNOPSIS 43.In stdlib.h 44.Ft int 45.Fn atoi "const char *nptr" 46.Sh DESCRIPTION 47The 48.Fn atoi 49function converts the initial portion of the string pointed to by 50.Fa nptr 51to 52.Li integer 53representation. 54.Pp 55It is equivalent to: 56.Bd -literal -offset indent 57(int)strtol(nptr, (char **)NULL, 10); 58.Ed 59.Sh SEE ALSO 60.Xr atof 3 , 61.Xr atol 3 , 62.Xr strtod 3 , 63.Xr strtol 3 , 64.Xr strtonum 3 , 65.Xr strtoul 3 66.Sh STANDARDS 67The 68.Fn atoi 69function conforms to 70.St -ansiC . 71.Sh HISTORY 72An 73.Fn atoi 74function first appeared in 75.At v1 . 76.Sh CAVEATS 77.Nm 78does no overflow checking, handles unsigned numbers poorly, 79and handles strings containing trailing extra characters 80(like 81.Dq "123abc" ) 82poorly. 83Careful use of 84.Xr strtol 3 85and 86.Xr strtoul 3 87can alleviate these problems, 88but 89.Xr strtonum 3 90can be used to convert numbers from strings much more safely 91and easily. 92