копировать область памяти (copy memory area)
Имя (Name)
memcpy - copy memory area
Синопсис (Synopsis)
#include <string.h>
void *memcpy(void *restrict dest, const void *restrict src, size_t n);
Описание (Description)
The memcpy() function copies n bytes from memory area src to
memory area dest. The memory areas must not overlap. Use
memmove(3) if the memory areas do overlap.
Возвращаемое значение (Return value)
The memcpy() function returns a pointer to dest.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│memcpy() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
Стандарты (Conforming to)
POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.
Примечание (Note)
Failure to observe the requirement that the memory areas do not
overlap has been the source of significant bugs. (POSIX and the
C standards are explicit that employing memcpy() with overlapping
areas produces undefined behavior.) Most notably, in glibc 2.13
a performance optimization of memcpy() on some platforms
(including x86-64) included changing the order in which bytes
were copied from src to dest.
This change revealed breakages in a number of applications that
performed copying with overlapping areas. Under the previous
implementation, the order in which the bytes were copied had
fortuitously hidden the bug, which was revealed when the copying
order was reversed. In glibc 2.14, a versioned symbol was added
so that old binaries (i.e., those linked against glibc versions
earlier than 2.14) employed a memcpy() implementation that safely
handles the overlapping buffers case (by providing an "older"
memcpy() implementation that was aliased to memmove(3)).
Смотри также (See also)
bcopy(3), bstring(3), memccpy(3), memmove(3), mempcpy(3),
strcpy(3), strncpy(3), wmemcpy(3)
