为什么 std::vector::iterator 不是连续的迭代器？

Question

根据std::vector的cppref page：

iterator LegacyRandomAccessIterator

也来自另一个cppref page:

The following standard library types are LegacyContiguousIterators:

vector::iterator for value_type other than bool.

哪个是正确的？

Answer 1

std::vector<T>::iterator（对于 T 而不是 bool）是一个连续的迭代器。

[vector.overview]/2:

A vector meets all of the requirements of a container and [...] for an element type other than bool, of a contiguous container.

[container.requirements.general]/13（强调我的）：

A contiguous container is a container whose member types iterator and const_iterator meet the Cpp17RandomAccessIterator requirements ([random.access.iterators]) and model contiguous_­iterator ([iterator.concept.contiguous]).

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According to the cppref page of std::vector:

iterator LegacyRandomAccessIterator

这并不意味着迭代器不是连续的迭代器。它甚至没有谈论连续迭代器。

同一页还提到：

std::vector (for T other than bool) meets the requirements of [...] ContiguousContainer [...].

并且 the page of ContiguousContainer 说：

The type X satisfies ContiguousContainer if

• [...]
• The member types X::iterator and X::const_iterator are LegacyContiguousIterators

Answer 2

两者都是正确的。所有向量迭代器都是随机访问迭代器。除了 vector of bool 之外的所有向量迭代器都是连续迭代器。请注意，所有连续迭代器也是随机访问迭代器。

前一个声明根本没有提供那么多信息，并且自从 c++17 引入了满足连续迭代器要求的名称的变化以来可能还没有更新。