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         /* 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 non
       standard 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/.



GNU                                       2011-09-28                                STRSTR(3)