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An allocator whose value type is the same as the container's value type.
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As a result of its using open addressing, the interface of `boost::unordered_flat_set` deviates in a number of aspects from that of `boost::unordered_flat_set`/`std::unordered_flat_set`:
由于采用开放定址，`boost::unordered_flat_set` 的接口在多个方面与 `boost::unordered_set`/`std::unordered_set` 存在差异：
- `value_type` must be move-constructible. - Pointer stability is not kept under rehashing. - `begin()` is not constant-time. - There is no API for bucket handling (except `bucket_count`) or node extraction/insertion. - The maximum load factor of the container is managed internally and can't be set by the user.
- `value_type` 必须可移动构造。
- 在重哈希过程中不保持指针稳定性。
- `begin()` 不是常数时间操作。
- 没有用于桶操作的 API（除了 `bucket_count`），也没有节点提取/插入的 API。
- 容器的最大负载因子由内部管理，用户无法设置。
Other than this, `boost::unordered_flat_set` is mostly a drop-in replacement of node-based standard unordered associative containers.
除此之外，`boost::unordered_flat_set` 基本上是基于节点的标准无序关联容器的直接替代品。
Synopsis
概要
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---
---
Description
描述
*Template Parameters*
*模板参数*
_Key_
_键_
`Key` must be https://en.cppreference.com/w/cpp/named_req/MoveInsertable[MoveInsertable^] into the container
`Key` 必须可以 https://en.cppreference.com/w/cpp/named_req/MoveInsertable[MoveInsertable^] 到容器中
and https://en.cppreference.com/w/cpp/named_req/Erasable[Erasable^] from the container.
并且可以从容器中 https://en.cppreference.com/w/cpp/named_req/Erasable[Erasable^]。
_Hash_
_Hash_
A unary function object type that acts a hash function for a `Key`. It takes a single argument of type `Key` and returns a value of type `std::size_t`.
一种一元函数对象类型，用作 `Key` 的哈希函数。它接受一个 `Key` 类型的参数，并返回一个 `std::size_t` 类型的值。
_Pred_
_Pred_
A binary function object that induces an equivalence relation on values of type `Key`. It takes two arguments of type `Key` and returns a value of type `bool`.
一种二元函数对象，用于在 `Key` 类型的值上建立等价关系。它接受两个 `Key` 类型的参数，并返回一个 `bool` 类型的值。
_Allocator_
_Allocator_
An allocator whose value type is the same as the container's value type.
一种分配器，其值类型与容器的值类型相同。
Allocators using https://en.cppreference.com/w/cpp/named_req/Allocator#Fancy_pointers[fancy pointers] are supported.
支持使用https://en.cppreference.com/w/cpp/named_req/Allocator#Fancy_pointers[fancy pointers] 的分配器。
The elements of the container are held into an internal _bucket array_. An element is inserted into a bucket determined by its hash code, but if the bucket is already occupied (a _collision_), an available one in the vicinity of the original position is used.
容器的元素保存在内部的**桶数组**中。元素根据其哈希码被插入到对应的桶中，但如果该桶已被占用（发生**冲突**），则会使用原始位置附近的一个可用桶。
The size of the bucket array can be automatically increased by a call to `insert`/`emplace`, or as a result of calling `rehash`/`reserve`. The _load factor_ of the container (number of elements divided by number of buckets) is never greater than `max_load_factor()`, except possibly for small sizes where the implementation may decide to allow for higher loads.
桶数组的大小可以通过调用 `insert`/`emplace` 自动增加，或者作为调用 `rehash`/`reserve` 的结果而增加。容器的**负载因子**（元素个数除以桶数量）永远不会大于 `max_load_factor()`，但在容量较小的情况下，实现可能会允许更高的负载。
If `link:../../../../../container_hash/doc/html/hash.html#ref_hash_is_avalanchinghash[hash_is_avalanching]<Hash>::value` is `true`, the hash function is used as-is; otherwise, a bit-mixing post-processing stage is added to increase the quality of hashing at the expense of extra computational cost.
如果`link:../../../../../container_hash/doc/html/hash.html#ref_hash_is_avalanching[hash_is_avalanching]<hash>::value` 为 `true`，则哈希函数将按原样使用；否则，将添加一个比特混合后处理阶段，以增加哈希质量，但会增加额外的计算成本。</hash>
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Configuration Macros
配置宏
`BOOST_UNORDERED_ENABLE_STATS`
`BOOST_UNORDERED_ENABLE_STATS`
Globally define this macro to enable xref:reference/stats.adoc#stats[statistics calculation] for the container. Note that this option decreases the overall performance of many operations.
全局定义此宏以启用容器的 xref:reference/stats.adoc#stats[统计信息计算]。请注意，此选项会降低许多操作的整体性能。
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Typedefs
类型定义
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A constant iterator whose value type is `value_type`.
一种常量迭代器，其值类型为 `value_type`。
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The iterator category is at least a forward iterator.
迭代器类别至少为前向迭代器。
Convertible to `const_iterator`.
可转换为 `const_iterator`。
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---
---
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A constant iterator whose value type is `value_type`.
一种常量迭代器，其值类型为 `value_type`。
English Chinese (Simplified Han script) Actions
```c++ float load_factor() const noexcept; ```
```c++ float load_factor() const noexcept; ```
Returns:;; `static_cast<float>(size())/static_cast<float>(bucket_count())`, or `0` if `bucket_count() == 0`.
返回：;; `static_cast<float>(size())/static_cast<float>(bucket_count())`，如果 `bucket_count() == 0` 则返回 `0`。</float></float>
max_load_factor
最大负载因子
```c++ void rehash(size_type n); ```
```c++ void rehash(size_type n); ```
Changes if necessary the size of the bucket array so that there are at least `n` buckets, and so that the load factor is less than or equal to the maximum load factor. When applicable, this will either grow or shrink the `bucket_count()` associated with the container.
必要时改变桶数组的大小，使得至少包含 `n` 个桶，并且负载因子小于或等于最大负载因子。在适用的情况下，这将增大或缩小与容器相关联的 `bucket_count()`。
When `size() == 0`, `rehash(0)` will deallocate the underlying buckets array. If the provided Allocator uses fancy pointers, a default allocation is subsequently performed.
当 `size() == 0` 时，`rehash(0)` 将释放底层桶数组的内存。如果所提供的分配器使用 fancy pointers，随后将执行一次默认分配。
```c++ template<class... Args> std::pair<iterator, bool> emplace(Args&&... args); ```
```c++ template<class... args=""> std::pair<iterator, bool=""> emplace(Args&amp;&amp;... args); ```</iterator,></class...>
`boost::unordered_flat_set` — An open-addressing unordered associative container that stores unique values.
`boost::unordered_flat_set` — 一种开放定址无序关联容器，用于存储唯一值。
The performance of `boost::unordered_flat_set` is much better than that of `boost::unordered_set` or other implementations of `std::unordered_set`. Unlike standard unordered associative containers, which are node-based, the elements of a `boost::unordered_flat_set` are held directly in the bucket array, and insertions into an already occupied bucket are diverted to available buckets in the vicinity of the original position. This type of data layout is known as _open addressing_.
`boost::unordered_flat_set` 的性能远优于 `boost::unordered_set` 或 `std::unordered_set` 的其他实现。与基于节点的标准无序关联容器不同，`boost::unordered_flat_set` 的元素直接保存在桶数组中，当插入位置已被占用时，会转移到原始位置附近可用的桶中。这种数据布局称为**开放定址**。
As a result of its using open addressing, the interface of `boost::unordered_flat_set` deviates in a number of aspects from that of `boost::unordered_flat_set`/`std::unordered_flat_set`:
由于采用开放定址，`boost::unordered_flat_set` 的接口在多个方面与 `boost::unordered_set`/`std::unordered_set` 存在差异：
- `value_type` must be move-constructible. - Pointer stability is not kept under rehashing. - `begin()` is not constant-time. - There is no API for bucket handling (except `bucket_count`) or node extraction/insertion. - The maximum load factor of the container is managed internally and can't be set by the user.
- `value_type` 必须可移动构造。
- 在重哈希过程中不保持指针稳定性。
- `begin()` 不是常数时间操作。
- 没有用于桶操作的 API（除了 `bucket_count`），也没有节点提取/插入的 API。
- 容器的最大负载因子由内部管理，用户无法设置。
_Key_
_键_
`Key` must be https://en.cppreference.com/w/cpp/named_req/MoveInsertable[MoveInsertable^] into the container
`Key` 必须可以 https://en.cppreference.com/w/cpp/named_req/MoveInsertable[MoveInsertable^] 到容器中
_Hash_
_Hash_
A unary function object type that acts a hash function for a `Key`. It takes a single argument of type `Key` and returns a value of type `std::size_t`.
一种一元函数对象类型，用作 `Key` 的哈希函数。它接受一个 `Key` 类型的参数，并返回一个 `std::size_t` 类型的值。
An allocator whose value type is the same as the container's value type.
一种分配器，其值类型与容器的值类型相同。
Allocators using https://en.cppreference.com/w/cpp/named_req/Allocator#Fancy_pointers[fancy pointers] are supported.
支持使用https://en.cppreference.com/w/cpp/named_req/Allocator#Fancy_pointers[fancy pointers] 的分配器。
The elements of the container are held into an internal _bucket array_. An element is inserted into a bucket determined by its hash code, but if the bucket is already occupied (a _collision_), an available one in the vicinity of the original position is used.
容器的元素保存在内部的**桶数组**中。元素根据其哈希码被插入到对应的桶中，但如果该桶已被占用（发生**冲突**），则会使用原始位置附近的一个可用桶。
The size of the bucket array can be automatically increased by a call to `insert`/`emplace`, or as a result of calling `rehash`/`reserve`. The _load factor_ of the container (number of elements divided by number of buckets) is never greater than `max_load_factor()`, except possibly for small sizes where the implementation may decide to allow for higher loads.
桶数组的大小可以通过调用 `insert`/`emplace` 自动增加，或者作为调用 `rehash`/`reserve` 的结果而增加。容器的**负载因子**（元素个数除以桶数量）永远不会大于 `max_load_factor()`，但在容量较小的情况下，实现可能会允许更高的负载。
If `link:../../../../../container_hash/doc/html/hash.html#ref_hash_is_avalanchinghash[hash_is_avalanching]<Hash>::value` is `true`, the hash function is used as-is; otherwise, a bit-mixing post-processing stage is added to increase the quality of hashing at the expense of extra computational cost.
如果`link:../../../../../container_hash/doc/html/hash.html#ref_hash_is_avalanching[hash_is_avalanching]<hash>::value` 为 `true`，则哈希函数将按原样使用；否则，将添加一个比特混合后处理阶段，以增加哈希质量，但会增加额外的计算成本。</hash>
Configuration Macros
配置宏
`BOOST_UNORDERED_ENABLE_STATS`
`BOOST_UNORDERED_ENABLE_STATS`
Globally define this macro to enable xref:reference/stats.adoc#stats[statistics calculation] for the container. Note that this option decreases the overall performance of many operations.
全局定义此宏以启用容器的 xref:reference/stats.adoc#stats[统计信息计算]。请注意，此选项会降低许多操作的整体性能。
Convertible to `const_iterator`.
可转换为 `const_iterator`。
```c++ explicit unordered_flat_set(size_type n, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& a = allocator_type()); ```
```c++ explicit unordered_flat_set(size_type n, const hasher&amp; hf = hasher(), const key_equal&amp; eql = key_equal(), const allocator_type&amp; a = allocator_type()); ```
Constructs an empty container with at least `n` buckets, using `hf` as the hash function, `eql` as the key equality predicate, and `a` as the allocator.
构造一个至少包含 `n` 个桶的空容器，使用 `hf` 作为哈希函数，`eql` 作为键相等谓词，`a` 作为分配器。
Iterator Range Constructor
迭代器范围构造函数
Constructs an empty container with at least `n` buckets, using `hf` as the hash function, `eql` as the key equality predicate and `a` as the allocator, and inserts the elements from `[f, l)` into it.
构造一个至少包含 `n` 个桶的空容器，使用 `hf` 作为哈希函数，`eql` 作为键相等谓词，`a` 作为分配器，并将 `[f, l)` 范围内的元素插入其中。
Copy Constructor
复制构造函数
```c++ unordered_flat_set(unordered_flat_set const& other); ```
```c++ unordered_flat_set(unordered_flat_set const&amp; other); ```

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Translation uploaded
An allocator whose value type is the same as the container's value type.
An allocator whose value type is the same as the container's value type.一种分配器，其值类型与容器的值类型相同。
06/05/2026
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String added in the repository
An allocator whose value type is the same as the container's value type.
An allocator whose value type is the same as the container's value type.
06/05/2026
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Glossary

English Chinese (Simplified Han script)
No related strings found in the glossary.

String information

Flags
safe-html, strict-same
Unit identifier
54177
Source string location
:248
String age
06/05/2026
Last updated
06/06/2026
Source string age
06/05/2026
Translation file AsciiDoc file
doc/modules/ROOT/pages/reference/unordered_flat_set_zh_Hans.adoc, string 20