memchr(3) [x11r4 man page]

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

NAME

       memchr, memrchr, rawmemchr - scan memory for a character

SYNOPSIS

       #include <string.h>

       void *memchr(const void *s, int c, size_t n);

       void *memrchr(const void *s, int c, size_t n);

       void *rawmemchr(const void *s, int c);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       memrchr(), rawmemchr(): _GNU_SOURCE

DESCRIPTION

       The  memchr()  function	scans the initial n bytes of the memory area pointed to by s for the first instance of c.  Both c and the bytes of
       the memory area pointed to by s are interpreted as unsigned char.

       The memrchr() function is like the memchr() function, except that it searches backward from the end of the n bytes pointed to by s  instead
       of forward from the beginning.

       The  rawmemchr()  function is similar to memchr(): it assumes (i.e., the programmer knows for certain) that an instance of c lies somewhere
       in the memory area starting at the location pointed to by s, and so performs an optimized search for c (i.e., no use of a count argument to
       limit  the  range  of the search).  If an instance of c is not found, the results are unpredictable.  The following call is a fast means of
       locating a string's terminating null byte:

	   char *p = rawmemchr(s, '');

RETURN VALUE

       The memchr() and memrchr() functions return a pointer to the matching byte or NULL if the character does not  occur  in	the  given  memory
       area.

       The rawmemchr() function returns a pointer to the matching byte, if one is found.  If no matching byte is found, the result is unspecified.

VERSIONS

       rawmemchr() first appeared in glibc in version 2.1.

       memrchr() first appeared in glibc in version 2.2.

ATTRIBUTES

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

       +---------------------------------+---------------+---------+
       |Interface			 | Attribute	 | Value   |
       +---------------------------------+---------------+---------+
       |memchr(), memrchr(), rawmemchr() | Thread safety | MT-Safe |
       +---------------------------------+---------------+---------+
CONFORMING TO

       memchr(): POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.

       The memrchr() function is a GNU extension, available since glibc 2.1.91.

       The rawmemchr() function is a GNU extension, available since glibc 2.1.

SEE ALSO

       bstring(3), ffs(3), index(3), memmem(3), rindex(3), strchr(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strstr(3), wmemchr(3)

COLOPHON

       This  page is part of release 4.15 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 https://www.kernel.org/doc/man-pages/.

								    2017-09-15								 MEMCHR(3)

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

NAME

       memchr, memrchr, rawmemchr - scan memory for a character

SYNOPSIS

       #include <string.h>

       void *memchr(const void *s, int c, size_t n);

       void *memrchr(const void *s, int c, size_t n);

       void *rawmemchr(const void *s, int c);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       memrchr(), rawmemchr(): _GNU_SOURCE

DESCRIPTION

       The  memchr()  function	scans the initial n bytes of the memory area pointed to by s for the first instance of c.  Both c and the bytes of
       the memory area pointed to by s are interpreted as unsigned char.

       The memrchr() function is like the memchr() function, except that it searches backward from the end of the n bytes pointed to by s  instead
       of forward from the beginning.

       The  rawmemchr()  function is similar to memchr(): it assumes (i.e., the programmer knows for certain) that an instance of c lies somewhere
       in the memory area starting at the location pointed to by s, and so performs an optimized search for c (i.e., no use of a count argument to
       limit  the  range  of the search).  If an instance of c is not found, the results are unpredictable.  The following call is a fast means of
       locating a string's terminating null byte:

	   char *p = rawmemchr(s, '');

RETURN VALUE

       The memchr() and memrchr() functions return a pointer to the matching byte or NULL if the character does not  occur  in	the  given  memory
       area.

       The rawmemchr() function returns a pointer to the matching byte, if one is found.  If no matching byte is found, the result is unspecified.

VERSIONS

       rawmemchr() first appeared in glibc in version 2.1.

       memrchr() first appeared in glibc in version 2.2.

ATTRIBUTES

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

       +---------------------------------+---------------+---------+
       |Interface			 | Attribute	 | Value   |
       +---------------------------------+---------------+---------+
       |memchr(), memrchr(), rawmemchr() | Thread safety | MT-Safe |
       +---------------------------------+---------------+---------+
CONFORMING TO

       memchr(): POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.

       The memrchr() function is a GNU extension, available since glibc 2.1.91.

       The rawmemchr() function is a GNU extension, available since glibc 2.1.

SEE ALSO

       bstring(3), ffs(3), index(3), memmem(3), rindex(3), strchr(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strstr(3), wmemchr(3)

COLOPHON

       This  page is part of release 4.15 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 https://www.kernel.org/doc/man-pages/.

								    2017-09-15								 MEMCHR(3)