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       memchr, memrchr, rawmemchr - scan memory for a character


       #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


       The  memchr()  function  scans  the  first  n  bytes of the memory area
       pointed to by s for the  character  c.   The  first  byte  to  match  c
       (interpreted as an unsigned character) stops the operation.

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

       The  rawmemchr() function is similar to memchr(): it assumes (i.e., the
       programmer knows for certain) that the character c  lies  somewhere  in
       the  string  s, and so performs an optimized search for the character c
       (i.e., no checking  for  the  terminating  null  byte,  or  use  of  an
       argument,  n, to limit the range of the search).  If the character c is
       not in the string s, then rawmemchr() may proceed to search beyond  the
       end of the string, and the result is unspecified.  The folowing call is
       a fast means of locating a string’s terminating null byte:

           char *p = rawmemchr(s, '\0');


       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.


       rawmemchr() first appeared in glibc in version 2.1.

       memrchr() first appeared in glibc in version 2.2.


       The memchr() function conforms to SVr4, 4.3BSD, C89, C99, POSIX.1-2001.

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

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


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


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