CINXE.COM
strstr
<html> <head> <title>strstr</title> <META NAME="KEYWORDS" CONTENT="strstr"> </head> <body BGCOLOR="#ffffff" LINK="#0000ff" VLINK="#0000ff" ALINK="#0000ff" TEXT="#000000"> <center> <h1><b>strstr</b></h1></center> <PRE> <STRONG><A HREF="/man3/STRSTR">STRSTR(3)</A></STRONG> Linux Programmer's Manual <STRONG><A HREF="/man3/STRSTR">STRSTR(3)</A></STRONG> NAME strstr, strcasestr - locate a substring SYNOPSIS #include <string.h> char *strstr(const char *haystack, const char *needle); #define _GNU_SOURCE /* See <STRONG><A HREF="/man7/feature_test_macros">feature_test_macros(7)</A></STRONG> */ #include <string.h> char *strcasestr(const char *haystack, const char *needle); DESCRIPTION The strstr() function finds the first occurrence of the substring nee- dle in the string haystack. The terminating null bytes ('\0') are not compared. The strcasestr() function is like strstr(), but ignores the case of both arguments. RETURN VALUE These functions return a pointer to the beginning of the located sub- string, or NULL if the substring is not found. ATTRIBUTES For an explanation of the terms used in this section, see at- <STRONG><A HREF="/man7/tributes">tributes(7)</A></STRONG>. +-------------+---------------+----------------+ |Interface | Attribute | Value | +-------------+---------------+----------------+ |strstr() | Thread safety | MT-Safe | +-------------+---------------+----------------+ |strcasestr() | Thread safety | MT-Safe locale | +-------------+---------------+----------------+ CONFORMING TO strstr(): POSIX.1-2001, POSIX.1-2008, C89, C99. The strcasestr() function is a nonstandard extension. SEE ALSO <STRONG><A HREF="/man3/index">index(3)</A></STRONG>, <STRONG><A HREF="/man3/memchr">memchr(3)</A></STRONG>, <STRONG><A HREF="/man3/memmem">memmem(3)</A></STRONG>, <STRONG><A HREF="/man3/rindex">rindex(3)</A></STRONG>, <STRONG><A HREF="/man3/strcasecmp">strcasecmp(3)</A></STRONG>, <STRONG><A HREF="/man3/strchr">strchr(3)</A></STRONG>, <STRONG><A HREF="/man3/string">string(3)</A></STRONG>, <STRONG><A HREF="/man3/strpbrk">strpbrk(3)</A></STRONG>, <STRONG><A HREF="/man3/strsep">strsep(3)</A></STRONG>, <STRONG><A HREF="/man3/strspn">strspn(3)</A></STRONG>, <STRONG><A HREF="/man3/strtok">strtok(3)</A></STRONG>, <STRONG><A HREF="/man3/wcsstr">wcsstr(3)</A></STRONG> COLOPHON This page is part of release 5.05 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. GNU 2019-03-06 <STRONG><A HREF="/man3/STRSTR">STRSTR(3)</A></STRONG></PRE> <center> <h6>Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2025 <a href="http://www.he.net">Hurricane Electric</a>. All Rights Reserved.</h6></center> </body> </html>