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 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, '\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.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| memchr (), memrchr (), rawmemchr () |
Thread safety |
MT-Safe |
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.
bstring(3),
ffs(3),
index(3),
memmem(3),
rindex(3),
strchr(3),
strpbrk(3),
strrchr(3),
strsep(3),
strspn(3),
strstr(3),
wmemchr(3)