c++ - 未初始化的数据和 memcpy

Question

Mike Miller 在 240. Uninitialized values and undefined behavior 中说:

The wording in 3.9.1 [basic.fundamental] was carefully crafted to allow use of unsigned char to access uninitialized data so that memcpy and such could be written in C++ without undefined behavior

这是什么意思？为什么要访问未初始化的数据？

Answer 1

当您复制包含填充的struct 时，memcpy 也会复制填充。通常，填充是未初始化的。