linux man page for strstr

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)