| MEMORY(3C) | Standard C Library Functions | MEMORY(3C) |
memory, memccpy,
memchr, memcmp,
memcpy, memmem,
memmove, memrchr,
memset — memory
operations
#include
<string.h>
void *
memccpy(void *restrict s1,
const void *restrict s2, int c,
size_t n);
void *
memchr(void *s,
int c, size_t n);
int
memcmp(const void *s1,
const void *s2, size_t n);
void *
memcpy(void *restrict s1,
const void *restrict s2, size_t
n);
void *
memmem(const void *l,
size_t l_len, const void *s,
size_t s_len);
void *
memmove(void *s1,
const void *s2, size_t n);
void *
memrchr(void *s,
int c, size_t n);
void *
memset(void *s,
int c, size_t n);
These functions operate as efficiently as possible on memory areas (arrays of bytes bounded by a count, not terminated by a null character). They do not check for the overflow of any receiving memory area.
The
memccpy()
function copies bytes from memory area s2 into
s1, stopping after the first occurrence of
c (converted to an unsigned
char) has been copied, or after n bytes have
been copied, whichever comes first. It returns a pointer to the byte after
the copy of c in s1, or a
NULL pointer if c was not
found in the first n bytes of
s2.
The
memchr()
function returns a pointer to the first occurrence of
c (converted to an unsigned
char) in the first n bytes (each interpreted as
an unsigned char) of memory area
s, or a NULL pointer if
c does not occur.
The
memrchr()
function behaves similarly to the memchr() function,
except that the memory area is searched in reverse from the last byte.
The
memcmp()
function compares its arguments, looking at the first
n bytes (each interpreted as an
unsigned char), and returns an integer less than,
equal to, or greater than 0, according as s1 is less
than, equal to, or greater than s2 when taken to be
unsigned characters.
The
memcpy()
function copies n bytes from memory area
s2 to s1 It returns
s1. If copying takes place between objects that
overlap, the behavior is undefined. In such cases, use
memmove() instead.
The
memmem()
function searches for the s_len long byte pattern
s in the memory region starting at
l for l_len bytes. If a match is
found, a pointer to the starting location in l is
returned. If no match is found, l_len is zero,
s_len is zero, or l_len is less
than s_len then a NULL pointer
is return.
The
memmove()
function copies n bytes from memory area
s2 to memory area s1. Copying
between objects that overlap will take place correctly. It returns
s1.
The
memset()
function sets the first n bytes in memory area
s to the value of c (converted
to an unsigned char). It returns
s.
Using memcpy() might be faster than using
memmove() if the application knows that the objects
being copied do not overlap.
Overlap between objects being copied can arise even when their (virtual) address ranges appear to be disjoint; for example, as a result of memory-mapping overlapping portions of the same underlying file, or of attaching the same shared memory segment more than once.
| January 25, 2022 | OmniOS |