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NAME

       strstr, strcasestr - locate a substring

SYNOPSIS

       #include <string.h>

       char *strstr(const char *haystack, const char *needle);

       #define _GNU_SOURCE         /* See feature_test_macros(7) */

       #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 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  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 correctly, 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)

COLOPHON

       This  page  is  part of release 3.35 of the Linux man-pages project.  A description of the
       project, and information about reporting bugs, can be found at  http://man7.org/linux/man-
       pages/.