> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/man/man9/memcpy.9.md).

# memcpy.9

`memcpy` — 复制内存中的字节

## 名称

`memcpy`, `memcpy_data`

## 概要

```c
#include <sys/systm.h>
```

```c
void *
memcpy(void *dst, const void *src, size_t len)

void *
memcpy_data(void *dst, const void *src, size_t len)
```

## 描述

`memcpy` 函数从对象 `src` 复制 `len` 字节到对象 `dst`，复制方式保留所复制对象中指针的来源（参见 [memory\_model(7)](/man/man7/memory_model.7.md)）。如果 `src` 和 `dst` 重叠，结果未定义。`memcpy_data` 函数执行相同操作，但不保留所复制对象中指针的来源。在 CHERI 目标上，会显式清除任何所复制能力的有效性标签。

## 返回值

`memcpy` 和 `memcpy_data` 函数返回 `dst` 的原始值。

## 参见

[bcopy(9)](/man/man9/bcopy.9.md), [memmove(9)](/man/man9/memmove.9.md), memmove\_data(9)

## 标准

`memcpy` 函数遵循 ISO/IEC 9899:1990（"ISO C89"）。

## 历史

`memcpy` 函数首次出现于 AT\&T System V UNIX，并为 4.3BSD 重新实现。`memcpy_data` 函数首次出现于 FreeBSD 16.0。


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