copy_backward 和 reverse_copy 的区别？

Question

我正在阅读 C++ primer，看到这两个函数似乎具有相同的功能。谁能帮忙告诉我这两者有什么区别？谢谢

Answer 1

reverse_copy实际上是将元素倒序排列。

1 2 3 4 5 - > 5 4 3 2 1 

copy_backward 简单地向后复制元素，但保留它们的相对顺序。

1 2 3 4 5 

5先复制，但放在最后一个位置。所以你的输出仍然是：

1 2 3 4 5

http://en.cppreference.com/w/cpp/algorithm/copy_backward

Copies the elements from the range, defined by [first, last), to another range ending at d_last. The elements are copied in reverse order (the last element is copied first), but their relative order is preserved.

http://en.cppreference.com/w/cpp/algorithm/reverse_copy

Copies the elements from the range [first, last) to another range beginning at d_first in such a way that the elements in the new range are in reverse order.

Answer 2

std::copy_backwards 是：

Copies the elements from the range, defined by [first, last), to another range ending at d_last. The elements are copied in reverse order (the last element is copied first), but their relative order is preserved.

std::reverse_copy

Copies the elements from the range [first, last) to another range beginning at d_first in such a way that the elements in the new range are in reverse order.

所以不同的是std::copy_backwards从最后开始复制，然后向后复制，保持原来的位置，而std::reverse_copy从头开始复制，但顺序相反。