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. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the University of 20.\" California, Berkeley and its contributors. 21.\" 4. Neither the name of the University nor the names of its contributors 22.\" may be used to endorse or promote products derived from this software 23.\" without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35.\" SUCH DAMAGE. 36.\" 37.\" @(#)strstr.3 8.1 (Berkeley) 6/4/93 38.\" $FreeBSD: src/lib/libc/string/strstr.3,v 1.3.2.5 2001/12/25 00:36:53 ache Exp $ 39.\" $DragonFly: src/lib/libc/string/strstr.3,v 1.5 2005/08/05 22:35:10 swildner Exp $ 40.\" 41.Dd October 11, 2001 42.Dt STRSTR 3 43.Os 44.Sh NAME 45.Nm strstr , 46.Nm strcasestr , 47.Nm strnstr 48.Nd locate a substring in a string 49.Sh LIBRARY 50.Lb libc 51.Sh SYNOPSIS 52.In string.h 53.Ft char * 54.Fn strstr "const char *big" "const char *little" 55.Ft char * 56.Fn strcasestr "const char *big" "const char *little" 57.Ft char * 58.Fn strnstr "const char *big" "const char *little" "size_t len" 59.Sh DESCRIPTION 60The 61.Fn strstr 62function 63locates the first occurrence of the null-terminated string 64.Fa little 65in the null-terminated string 66.Fa big . 67.Pp 68The 69.Fn strcasestr 70function is similar to 71.Fn strstr , 72but ignores the case of both strings. 73.Pp 74The 75.Fn strnstr 76function 77locates the first occurrence of the null-terminated string 78.Fa little 79in the string 80.Fa big , 81where not more than 82.Fa len 83characters are searched. 84Characters that appear after a 85.Ql \e0 86character are not searched. 87Since the 88.Fn strnstr 89function is a 90.Fx 91/ 92.Dx 93specific API, it should only be used when portability is not a concern. 94.Sh RETURN VALUES 95If 96.Fa little 97is an empty string, 98.Fa big 99is returned; 100if 101.Fa little 102occurs nowhere in 103.Fa big , 104.Dv NULL 105is returned; 106otherwise a pointer to the first character of the first occurrence of 107.Fa little 108is returned. 109.Sh EXAMPLES 110The following sets the pointer 111.Va ptr 112to the 113.Qq Li Bar Baz 114portion of 115.Va largestring : 116.Bd -literal -offset indent 117const char *largestring = "Foo Bar Baz"; 118const char *smallstring = "Bar"; 119char *ptr; 120 121ptr = strstr(largestring, smallstring); 122.Ed 123.Pp 124The following sets the pointer 125.Va ptr 126to 127.Dv NULL , 128because only the first 4 characters of 129.Va largestring 130are searched: 131.Bd -literal -offset indent 132const char *largestring = "Foo Bar Baz"; 133const char *smallstring = "Bar"; 134char *ptr; 135 136ptr = strnstr(largestring, smallstring, 4); 137.Ed 138.Sh SEE ALSO 139.Xr memchr 3 , 140.Xr strchr 3 , 141.Xr strcspn 3 , 142.Xr strpbrk 3 , 143.Xr strrchr 3 , 144.Xr strsep 3 , 145.Xr strspn 3 , 146.Xr strtok 3 147.Sh STANDARDS 148The 149.Fn strstr 150function 151conforms to 152.St -isoC . 153