1.\" $OpenBSD: strstr.3,v 1.12 2013/06/05 03:39:23 tedu Exp $ 2.\" 3.\" Copyright (c) 1990, 1991 The Regents of the University of California. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Chris Torek and the American National Standards Committee X3, 8.\" on Information Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.Dd $Mdocdate: June 5 2013 $ 35.Dt STRSTR 3 36.Os 37.Sh NAME 38.Nm strstr , strcasestr 39.Nd locate a substring in a string 40.Sh SYNOPSIS 41.In string.h 42.Ft char * 43.Fn strstr "const char *big" "const char *little" 44.Ft char * 45.Fn strcasestr "const char *big" "const char *little" 46.Sh DESCRIPTION 47The 48.Fn strstr 49function locates the first occurrence of the NUL-terminated string 50.Fa little 51in the NUL-terminated string 52.Fa big . 53.Pp 54The 55.Fn strcasestr 56function is similar to 57.Fn strstr 58but ignores the case of both strings. 59.Pp 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 SEE ALSO 75.Xr memchr 3 , 76.Xr strchr 3 , 77.Xr strcspn 3 , 78.Xr strpbrk 3 , 79.Xr strrchr 3 , 80.Xr strsep 3 , 81.Xr strspn 3 , 82.Xr strtok 3 , 83.Xr wcsstr 3 84.Sh STANDARDS 85The 86.Fn strstr 87function conforms to 88.St -ansiC . 89.Sh HISTORY 90The 91.Fn strstr 92function first appeared in 93.Bx 4.3 Reno . 94The 95.Fn strcasestr 96function appeared in glibc 2.1, 97was reimplemented for 98.Fx 4.5 99and ported to 100.Ox 3.8 . 101