strstr(3) — Linux manual page


STRSTR(3)               Linux Programmer's Manual              STRSTR(3)

NAME         top

       strstr, strcasestr - locate a substring

SYNOPSIS         top

       #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         top

       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         top

       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         top

       For an explanation of the terms used in this section, see

       │Interface                      Attribute     Value          │
       │strstr()                       │ Thread safety │ MT-Safe        │
       │strcasestr()                   │ Thread safety │ MT-Safe locale │

CONFORMING TO         top

       strstr(): POSIX.1-2001, POSIX.1-2008, C89, C99.

       The strcasestr() function is a nonstandard extension.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at

GNU                            2021-08-27                      STRSTR(3)

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