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 1.12 2015/09/10 15:16:43 schwarze Exp $ 33.\" 34.Dd $Mdocdate: September 10 2015 $ 35.Dt ATOI 3 36.Os 37.Sh NAME 38.Nm atoi 39.Nd convert ASCII string to integer 40.Sh SYNOPSIS 41.In stdlib.h 42.Ft int 43.Fn atoi "const char *nptr" 44.Sh DESCRIPTION 45The 46.Fn atoi 47function converts the initial portion of the string pointed to by 48.Fa nptr 49to 50.Li integer 51representation. 52.Pp 53It is equivalent to: 54.Bd -literal -offset indent 55(int)strtol(nptr, (char **)NULL, 10); 56.Ed 57.Sh SEE ALSO 58.Xr atof 3 , 59.Xr atol 3 , 60.Xr strtod 3 , 61.Xr strtol 3 , 62.Xr strtonum 3 , 63.Xr strtoul 3 64.Sh STANDARDS 65The 66.Fn atoi 67function conforms to 68.St -ansiC . 69.Sh HISTORY 70An 71.Fn atoi 72function first appeared in 73.At v1 . 74.Sh CAVEATS 75.Nm 76does no overflow checking, handles unsigned numbers poorly, 77and handles strings containing trailing extra characters 78(like 79.Dq "123abc" ) 80poorly. 81Careful use of 82.Xr strtol 3 83and 84.Xr strtoul 3 85can alleviate these problems, 86but 87.Xr strtonum 3 88can be used to convert numbers from strings much more safely 89and easily. 90