1.\" $OpenBSD: strnstr.9,v 1.1 2023/12/21 02:57:14 jsg Exp $ 2.\" 3.\" Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org> 4.\" Copyright (c) 1990, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" This code is derived from software contributed to Berkeley by 8.\" Chris Torek and the American National Standards Committee X3, 9.\" on Information Processing Systems. 10.\" 11.\" Redistribution and use in source and binary forms, with or without 12.\" modification, are permitted provided that the following conditions 13.\" are met: 14.\" 1. Redistributions of source code must retain the above copyright 15.\" notice, this list of conditions and the following disclaimer. 16.\" 2. Redistributions in binary form must reproduce the above copyright 17.\" notice, this list of conditions and the following disclaimer in the 18.\" documentation and/or other materials provided with the distribution. 19.\" 3. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.Dd $Mdocdate: December 21 2023 $ 36.Dt STRNSTR 9 37.Os 38.Sh NAME 39.Nm strnstr 40.Nd locate a substring in a string 41.Sh SYNOPSIS 42.In lib/libkern/libkern.h 43.Ft char * 44.Fn strnstr "const char *big" "const char *little" "size_t len" 45.Sh DESCRIPTION 46The 47.Fn strnstr 48function 49locates the first occurrence of the null-terminated string 50.Fa little 51in the string 52.Fa big , 53where not more than 54.Fa len 55characters are searched. 56Characters that appear after a 57.Ql \e0 58character are not searched. 59.Sh RETURN VALUES 60If 61.Fa little 62is an empty string, 63.Fa big 64is returned; 65if 66.Fa little 67occurs nowhere in 68.Fa big , 69.Dv NULL 70is returned; 71otherwise a pointer to the first character of the first occurrence of 72.Fa little 73is returned. 74.Sh EXAMPLES 75The following sets the pointer 76.Va ptr 77to 78.Dv NULL , 79because only the first 4 characters of 80.Va largestring 81are searched: 82.Bd -literal -offset indent 83const char *largestring = "Foo Bar Baz"; 84const char *smallstring = "Bar"; 85char *ptr; 86 87ptr = strnstr(largestring, smallstring, 4); 88.Ed 89.Sh SEE ALSO 90.Xr memchr 9 91