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.Dd October 11, 2001 34.Dt STRSTR 3 35.Os 36.Sh NAME 37.Nm strstr , strcasestr , strnstr 38.Nd locate a substring in a string 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In string.h 43.Ft char * 44.Fn strstr "const char *big" "const char *little" 45.Ft char * 46.Fn strcasestr "const char *big" "const char *little" 47.Ft char * 48.Fn strnstr "const char *big" "const char *little" "size_t len" 49.In string.h 50.In xlocale.h 51.Ft char * 52.Fn strcasestr_l "const char *big" "const char *little" "locale_t loc" 53.Sh DESCRIPTION 54The 55.Fn strstr 56function 57locates the first occurrence of the null-terminated string 58.Fa little 59in the null-terminated string 60.Fa big . 61.Pp 62The 63.Fn strcasestr 64function is similar to 65.Fn strstr , 66but ignores the case of both strings. 67.Pp 68The 69.Fn strcasestr_l 70function does the same as 71.Fn strcasestr 72but takes an explicit locale rather than using the current locale. 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 91specific API, it should only be used when portability is not a concern. 92.Sh RETURN VALUES 93If 94.Fa little 95is an empty string, 96.Fa big 97is returned; 98if 99.Fa little 100occurs nowhere in 101.Fa big , 102.Dv NULL 103is returned; 104otherwise a pointer to the first character of the first occurrence of 105.Fa little 106is returned. 107.Sh EXAMPLES 108The following sets the pointer 109.Va ptr 110to the 111.Qq Li Bar Baz 112portion of 113.Va largestring : 114.Bd -literal -offset indent 115const char *largestring = "Foo Bar Baz"; 116const char *smallstring = "Bar"; 117char *ptr; 118 119ptr = strstr(largestring, smallstring); 120.Ed 121.Pp 122The following sets the pointer 123.Va ptr 124to 125.Dv NULL , 126because only the first 4 characters of 127.Va largestring 128are searched: 129.Bd -literal -offset indent 130const char *largestring = "Foo Bar Baz"; 131const char *smallstring = "Bar"; 132char *ptr; 133 134ptr = strnstr(largestring, smallstring, 4); 135.Ed 136.Sh SEE ALSO 137.Xr memchr 3 , 138.Xr memmem 3 , 139.Xr strchr 3 , 140.Xr strcspn 3 , 141.Xr strpbrk 3 , 142.Xr strrchr 3 , 143.Xr strsep 3 , 144.Xr strspn 3 , 145.Xr strtok 3 , 146.Xr wcsstr 3 147.Sh STANDARDS 148The 149.Fn strstr 150function 151conforms to 152.St -isoC . 153.Sh HISTORY 154The 155.Fn strnstr 156function was introduced by 157.Fx 4.5 158and is non-standard. 159