std::copy 是否处理重叠范围?

Does std::copy handle overlapping ranges?(std::copy 是否处理重叠范围?)

问题描述

将数据从一个范围复制到另一个范围时，您必须小心源范围和目标范围之间是否存在部分重叠.如果目标范围的开头与源范围的尾部重叠，则纯顺序副本将使数据出现乱码.C 运行时库除了 memcpy 之外还有 memmove 来处理此类重叠问题.

When copying data from one range to another, you have to be careful if there's partial overlap between the source and destination ranges. If the beginning of the destination range overlaps the tail of the source range, a plain sequential copy will garble the data. The C run-time library has memmove in addition to memcpy to handle such overlap problems.

我假设 std::copy 像 memcpy 一样工作，因为它不考虑源区域和目标区域之间的重叠.如果您尝试使用 std::copy 在 std::vector 中向下"移动对象，则会损坏数据.是否有类似 memmove 的 STL 算法来处理这种情况?还是我应该使用反向迭代器自己动手?

I assume std::copy works like memcpy, in that it doesn't pay any regard to overlap between the source and destination regions. If you try to shift objects "down" in a std::vector with std::copy, you'll corrupt the data. Is there an STL algorithm analogue of memmove to handle situations like this? Or should I roll my own with reverse iterators?

推荐答案

如果输出范围的开头与输入范围重叠，则不处理重叠范围.

It doesn't handle overlapping ranges iff the beginning of the output range overlaps with the input range.

幸运的是，您可以使用 std::copy_backward 代替(这要求您不要将输出范围的 end 与输入范围重叠).

Fortunately, you can use std::copy_backward instead (which requires that you don't overlap the end of the output range with the input range).

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