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 (inter-
preted as an unsigned character) stops the operation.
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 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 argu-
ment, 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 following 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.
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