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.\" 4. 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.\" @(#)strstr.3 8.1 (Berkeley) 6/4/93 34.\" $FreeBSD$ 35.\" 36.Dd October 11, 2001 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 null-terminated string 57.Fa little 58in the null-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. 66.Pp 67The 68.Fn strnstr 69function 70locates the first occurrence of the null-terminated string 71.Fa little 72in the string 73.Fa big , 74where not more than 75.Fa len 76characters are searched. 77Characters that appear after a 78.Ql \e0 79character are not searched. 80Since the 81.Fn strnstr 82function is a 83.Fx 84specific API, it should only be used when portability is not a concern. 85.Sh RETURN VALUES 86If 87.Fa little 88is an empty string, 89.Fa big 90is returned; 91if 92.Fa little 93occurs nowhere in 94.Fa big , 95.Dv NULL 96is returned; 97otherwise a pointer to the first character of the first occurrence of 98.Fa little 99is returned. 100.Sh EXAMPLES 101The following sets the pointer 102.Va ptr 103to the 104.Qq Li Bar Baz 105portion of 106.Va largestring : 107.Bd -literal -offset indent 108const char *largestring = "Foo Bar Baz"; 109const char *smallstring = "Bar"; 110char *ptr; 111 112ptr = strstr(largestring, smallstring); 113.Ed 114.Pp 115The following sets the pointer 116.Va ptr 117to 118.Dv NULL , 119because only the first 4 characters of 120.Va largestring 121are searched: 122.Bd -literal -offset indent 123const char *largestring = "Foo Bar Baz"; 124const char *smallstring = "Bar"; 125char *ptr; 126 127ptr = strnstr(largestring, smallstring, 4); 128.Ed 129.Sh SEE ALSO 130.Xr memchr 3 , 131.Xr memmem 3 , 132.Xr strchr 3 , 133.Xr strcspn 3 , 134.Xr strpbrk 3 , 135.Xr strrchr 3 , 136.Xr strsep 3 , 137.Xr strspn 3 , 138.Xr strtok 3 139.Sh STANDARDS 140The 141.Fn strstr 142function 143conforms to 144.St -isoC . 145