strstr(3) — Linux manual page

strstr(3)               Library Functions Manual               strstr(3)

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)

COLOPHON

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Linux man-pages 6.9.1          2024-06-15                      strstr(3)

Pages that refer to this page: memchr(3), memmem(3), strchr(3), string(3), strpbrk(3), strsep(3), strspn(3), strtok(3), wcsstr(3), signal-safety(7)

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