NAME

       strstr, strcasestr - locate a substring

LIBRARY

       Standard C library (libc, -lc)

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 located substring, or NULL if the
       substring is not found.

       If needle is the empty string, the return value is always haystack itself.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────────────────────────────────────────┬───────────────┬────────────────┐
       │Interface                                               │ Attribute     │ Value          │
       ├────────────────────────────────────────────────────────┼───────────────┼────────────────┤
       │strstr()                                                │ Thread safety │ MT-Safe        │
       ├────────────────────────────────────────────────────────┼───────────────┼────────────────┤
       │strcasestr()                                            │ Thread safety │ MT-Safe locale │
       └────────────────────────────────────────────────────────┴───────────────┴────────────────┘

STANDARDS

       strstr()
              C11, POSIX.1-2008.

       strcasestr()
              GNU.

HISTORY

       strstr()
              POSIX.1-2001, C89.

       strcasestr()
              GNU.

SEE ALSO

       memchr(3),   memmem(3),   strcasecmp(3),   strchr(3),  string(3),  strpbrk(3),  strsep(3),
       strspn(3), strtok(3), wcsstr(3)