STRSTR(3) Linux Programmer's Manual STRSTR(3)
NAME
strstr, strcasestr - locate a substring
SYNOPSIS
#include <string.h>
char *strstr(const char *haystack, const char *needle);
#define _GNU_SOURCE
#include <string.h>
char *strcasestr(const char *haystack, const char *needle);
DESCRIPTION
The strstr() function finds the first occurrence of the substring needle in the string haystack. The terminating ' ' characters 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 substring, or NULL if the substring is not found.
CONFORMING TO
The strstr() function conforms to C89 and C99. The strcasestr() function is a nonstandard extension.
BUGS
Early versions of Linux libc (like 4.5.26) would not allow an empty needle argument for strstr(). Later versions (like 4.6.27) work cor-
rectly, and return haystack when needle is empty.
SEE ALSO
index(3), memchr(3), rindex(3), strcasecmp(3), strchr(3), string(3), strpbrk(3), strsep(3), strspn(3), strtok(3), wcsstr(3), fea-
ture_test_macros(7)
COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU
2010-09-20 STRSTR(3)
