[#bsl-set-0d]
= xref:bsl.adoc[bsl]::set
:relfileprefix: ../
:mrdocs:

This class template implements a value‐semantic container type holding an ordered sequence of unique keys (of the template parameter type, `KEY`).

== Synopsis

Declared in `<bslstl_set.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class KEY,
    class COMPARATOR = std::less<KEY>,
    class ALLOCATOR = xref:bsl/allocator-0df.adoc[allocator<KEY>]>
class set;
----

== Description

This class: * supports a complete set of _value‐semantic_ operations except for `BDEX` serialization * is _exception‐neutral_ (agnostic except for the `at` method) * is _alias‐safe_ * is `const` _thread‐safe_ For terminology see {`bsldoc_glossary`}.

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:bsl/set-0d/allocator_type.adoc[`allocator_type`] 
| This `typedef` is an alias to the (template parameter) `ALLOCATOR`.
| xref:bsl/set-0d/const_iterator.adoc[`const_iterator`] 
| This `typedef` is an alias to `iterator`.
| xref:bsl/set-0d/const_pointer.adoc[`const_pointer`] 
| This `typedef` is an alias to the allocator const‐pointer type.
| xref:bsl/set-0d/const_reference.adoc[`const_reference`] 
| This `typedef` is an alias for `const_reference`.
| xref:bsl/set-0d/const_reverse_iterator.adoc[`const_reverse_iterator`] 
| This `typedef` is an alias to the const reverse iterator type.
| xref:bsl/set-0d/difference_type.adoc[`difference_type`] 
| This `typedef` is an alias to the allocator difference type.
| xref:bsl/set-0d/iterator.adoc[`iterator`] 
| This `typedef` is an alias to the red‐black tree iterator type.
| xref:bsl/set-0d/key_compare.adoc[`key_compare`] 
| This `typedef` is an alias to the (template parameter) `COMPARATOR`.
| xref:bsl/set-0d/key_type.adoc[`key_type`] 
| This `typedef` is an alias to the (template parameter) `KEY` type.
| xref:bsl/set-0d/pointer.adoc[`pointer`] 
| This `typedef` is an alias to the allocator pointer type.
| xref:bsl/set-0d/reference.adoc[`reference`] 
| This `typedef` is an alias to `value_type&`.
| xref:bsl/set-0d/reverse_iterator.adoc[`reverse_iterator`] 
| This `typedef` is an alias to the reverse iterator type.
| xref:bsl/set-0d/size_type.adoc[`size_type`] 
| This `typedef` is an alias to the allocator size type.
| xref:bsl/set-0d/value_compare.adoc[`value_compare`] 
| This `typedef` is an alias to `key_compare`.
| xref:bsl/set-0d/value_type.adoc[`value_type`] 
| This `typedef` is an alias to `key_type`.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/set-0d/2constructor-006.adoc[`set`]         [.small]#[constructor]#
| Constructors
| xref:bsl/set-0d/2destructor.adoc[`~set`] [.small]#[destructor]#
| Destroy this object.
| xref:bsl/set-0d/operator_assign-06.adoc[`operator=`] 
| Assignment operators
| xref:bsl/set-0d/begin-054.adoc[`begin`] 
| `begin` overloads
| xref:bsl/set-0d/cbegin.adoc[`cbegin`] 
| Return a const iterator to the first element, or `cend` if empty.
| xref:bsl/set-0d/cend.adoc[`cend`] 
| Return an iterator providing non‐modifiable access to the past‐the‐end element in the ordered sequence of `value_type` objects maintained by this set.
| xref:bsl/set-0d/clear.adoc[`clear`] 
| Remove all entries from this set. Note that the set is empty after this call, but allocated memory may be retained for future use.
| xref:bsl/set-0d/contains-0b.adoc[`contains`] 
| `contains` overloads
| xref:bsl/set-0d/count-0a3.adoc[`count`] 
| `count` overloads
| xref:bsl/set-0d/crbegin.adoc[`crbegin`] 
| Return a const reverse iterator to the last element, or `crend`.
| xref:bsl/set-0d/crend.adoc[`crend`] 
| Return a const reverse iterator to prior‐to‐the‐beginning.
| xref:bsl/set-0d/emplace.adoc[`emplace`] 
| Emplace a newly constructed `value_type` if not already present.
| xref:bsl/set-0d/emplace_hint.adoc[`emplace_hint`] 
| Emplace a newly constructed `value_type` near `hint` if not present.
| xref:bsl/set-0d/empty.adoc[`empty`] 
| Return `true` if this set contains no elements, and `false` otherwise.
| xref:bsl/set-0d/end-0c.adoc[`end`] 
| `end` overloads
| xref:bsl/set-0d/equal_range-07.adoc[`equal_range`] 
| `equal_range` overloads
| xref:bsl/set-0d/erase-05.adoc[`erase`] 
| `erase` overloads
| xref:bsl/set-0d/find-0a.adoc[`find`] 
| `find` overloads
| xref:bsl/set-0d/get_allocator.adoc[`get_allocator`] 
| Return (a copy of) the allocator used for memory allocation by this set.
| xref:bsl/set-0d/insert-00a.adoc[`insert`] 
| `insert` overloads
| xref:bsl/set-0d/insert_range.adoc[`insert_range`] 
| Insert each unique value from the specified `range`.
| xref:bsl/set-0d/key_comp.adoc[`key_comp`] 
| Return the key‐comparison functor used by this set.
| xref:bsl/set-0d/lower_bound-0b.adoc[`lower_bound`] 
| `lower_bound` overloads
| xref:bsl/set-0d/max_size.adoc[`max_size`] 
| Return a theoretical upper bound on this set's size.
| xref:bsl/set-0d/rbegin-08.adoc[`rbegin`] 
| `rbegin` overloads
| xref:bsl/set-0d/rend-0b.adoc[`rend`] 
| `rend` overloads
| xref:bsl/set-0d/size.adoc[`size`] 
| Return the number of elements in this set.
| xref:bsl/set-0d/swap.adoc[`swap`] 
| Exchange the value and comparator with `other`.
| xref:bsl/set-0d/upper_bound-0c.adoc[`upper_bound`] 
| `upper_bound` overloads
| xref:bsl/set-0d/value_comp.adoc[`value_comp`] 
| Return a functor for comparing two `value_type` objects.
|===


== Deduction Guides

[cols="1,4"]
|===
| Name| Description
| xref:bsl/set-03.adoc[`set<KEY>`] 
| Deduce `KEY` from an initializer_list when an allocator pointer is given.
| xref:bsl/set-051.adoc[`set<KEY>`] 
| Deduce `KEY` from iterators when an allocator pointer is supplied.
| xref:bsl/set-09.adoc[`set<KEY, COMPARATOR>`] 
| Deduce `KEY` and `COMPARATOR` from an initializer_list with an allocator pointer.
| xref:bsl/set-0f9.adoc[`set<KEY, COMPARATOR>`] 
| Deduce `KEY` and `COMPARATOR` from iterators when an allocator pointer is given.
| xref:bsl/set-0f6.adoc[`set<KEY, COMPARATOR, ALLOCATOR>`] 
| Deduce `KEY`, `COMPARATOR`, and `ALLOCATOR` from an initializer_list constructor.
| xref:bsl/set-0a.adoc[`set<KEY, COMPARATOR, ALLOCATOR>`] 
| Deduce `KEY`, `COMPARATOR`, and `ALLOCATOR` from an iterator‐range constructor.
| xref:bsl/set-05a.adoc[`set<KEY, std::less<KEY>, ALLOCATOR>`] 
| Deduce `KEY` and `ALLOCATOR` from an initializer_list constructor.
| xref:bsl/set-0b.adoc[`set<KEY, std::less<KEY>, ALLOCATOR>`] 
| Deduce `KEY` and `ALLOCATOR` from an iterator‐range constructor.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/erase_if-04.adoc[`erase_if`]
| Erase all elements in `s` that satisfy `predicate`.
| xref:bsl/operator_3way-0da.adoc[`operator<=>`]
| Perform a lexicographic three‐way comparison of `lhs` and `rhs`.
| xref:bsl/operator_eq-045.adoc[`operator==`]
| Return `true` if `lhs` and `rhs` have the same value, and `false` otherwise.
| xref:bsl/swap-0c8.adoc[`swap`]
| Exchange the value and comparator of `a` with those of `b`.
|===


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