1.\" Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org> 2.\" Copyright (c) 1990, 1991, 1993 3.\" The Regents of the University of California. All rights reserved. 4.\" 5.\" This code is derived from software contributed to Berkeley by 6.\" Chris Torek and the American National Standards Committee X3, 7.\" on Information Processing Systems. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" from: @(#)strstr.3 8.1 (Berkeley) 6/4/93 34.\" $NetBSD: strstr.3,v 1.12 2014/09/24 18:43:21 wiz Exp $ 35.\" 36.Dd September 24, 2014 37.Dt STRSTR 3 38.Os 39.Sh NAME 40.Nm strstr , strcasestr , strnstr 41.Nd locate a substring in a string 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In string.h 46.Ft char * 47.Fn strstr "const char *big" "const char *little" 48.Ft char * 49.Fn strcasestr "const char *big" "const char *little" 50.Ft char * 51.Fn strnstr "const char *big" "const char *little" "size_t len" 52.Sh DESCRIPTION 53The 54.Fn strstr 55function 56locates the first occurrence of the nul-terminated string 57.Fa little 58in the nul-terminated string 59.Fa big . 60.Pp 61The 62.Fn strcasestr 63function is similar to 64.Fn strstr , 65but ignores the case of both strings. 66The 67.Fn strnstr 68function 69locates the first occurrence of the NUL-terminated string 70.Fa little 71in the string 72.Fa big , 73where not more than 74.Fa len 75characters are searched. 76Characters that appear after a 77.Ql \e0 78character are not searched. 79Since the 80.Fn strnstr 81function is a 82.Nx 83specific API, it should only be used when portability is not a concern. 84.Sh RETURN VALUES 85If 86.Fa little 87is an empty string, 88.Fa big 89is returned; 90if 91.Fa little 92occurs nowhere in 93.Fa big , 94.Dv NULL 95is returned; 96otherwise a pointer to the first character of the first occurrence of 97.Fa little 98is returned. 99.Sh EXAMPLES 100The following sets the pointer 101.Va ptr 102to the 103.Qq Li Bar Baz 104portion of 105.Va largestring : 106.Bd -literal -offset indent 107const char *largestring = "Foo Bar Baz"; 108const char *smallstring = "Bar"; 109char *ptr; 110 111ptr = strstr(largestring, smallstring); 112.Ed 113.Sh SEE ALSO 114.Xr index 3 , 115.Xr memchr 3 , 116.Xr rindex 3 , 117.Xr strchr 3 , 118.Xr strcspn 3 , 119.Xr strpbrk 3 , 120.Xr strrchr 3 , 121.Xr strsep 3 , 122.Xr strspn 3 , 123.Xr strtok 3 124.Sh STANDARDS 125The 126.Fn strstr 127function 128conforms to 129.St -isoC . 130.Sh HISTORY 131The 132.Fn strnstr 133function originated in 134.Fx . 135