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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

       #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 '\0' 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
       correctly, and return haystack when needle is empty.

SEE ALSO

       index(3), memchr(3), rindex(3), strcasecmp(3),  strchr(3),  strpbrk(3),
       strsep(3), strspn(3), strtok(3), wcsstr(3), feature_test_macros(7)

COLOPHON

       This  page  is  part of release 3.24 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/.