NAME¶

std::unordered_set::bucket - std::unordered_set::bucket

Synopsis¶

size_type bucket( const Key& key ) const; (1) (since C++11)
template< typename K > (2) (since C++26)
size_type bucket( const K& x ) const;

1) Returns the index of the bucket for key key. Elements (if any) with keys
equivalent to key are always found in this bucket.
2) Returns the index of the bucket for key that compares equivalent to the value x.
Elements (if any) with keys that compare equivalent to x are always found in this
bucket. This overload participates in overload resolution only if
Hash::is_transparent and KeyEqual::is_transparent are valid and each denotes a type.
This assumes that such Hash is callable with both K and Key type, and that the
KeyEqual is transparent, which, together, allows calling this function without
constructing an instance of Key.

The returned value is valid only for instances of the container for which
bucket_count() returns the same value (e.g., rehash() invalidates previously
obtained value).

The behavior is undefined if bucket_count() is zero.

Parameters¶

key - the value of the key to examine
x - a value of any type that can be transparently compared with a key

Return value¶

Bucket index for the requested key.

Complexity¶

Constant.

Notes¶

Feature-test macro Value Std Feature
Heterogeneous
overloads for the
remaining member
__cpp_lib_associative_heterogeneous_insertion 202311L (C++26) functions in ordered
and unordered
associative
containers. (2)

Example¶

This section is incomplete
Reason: no example

See also¶

bucket_size returns the number of elements in specific bucket
(public member function)

Category:¶

* Todo no example