NAME¶

deductionguidesforstd::set - deductionguidesforstd::set

Synopsis¶

Defined in header <set>
template<

class InputIt,
class Comp = std::less<typename
std::iterator_traits<InputIt>::value_type>,
class Alloc = std::allocator<typename (1) (since C++17)
std::iterator_traits<InputIt>::value_type>>
set( InputIt, InputIt, Comp = Comp(), Alloc = Alloc() )

-> set<typename std::iterator_traits<InputIt>::value_type,
Comp, Alloc>;
template<

class Key, class Comp = std::less<Key>,
class Alloc = std::allocator<Key> > (2) (since C++17)
set( std::initializer_list<Key>, Comp = Comp(), Alloc = Alloc() )

-> set<Key, Comp, Alloc>;
template< class InputIt, class Alloc >

set( InputIt, InputIt, Alloc )
-> set<typename std::iterator_traits<InputIt>::value_type, (3) (since C++17)

std::less<typename
std::iterator_traits<InputIt>::value_type>, Alloc>;
template< class Key, class Alloc >

set( std::initializer_list<Key>, Alloc ) (4) (since C++17)

-> set<Key, std::less<Key>, Alloc>;
template< ranges::input_range R, class Compare =
less<ranges::range_value_t<R>>,

class Alloc = std::allocator<ranges::range_value_t<R>> > (5) (since C++23)
set( std::from_range_t, R&&, Compare = Compare(), Alloc = Alloc()
)

-> set<ranges::range_value_t<R>, Compare, Alloc>;
template< ranges::input_range R, class Alloc >

set( std::from_range_t, R&&, Alloc ) (6) (since C++23)

-> set<ranges::range_value_t<R>,
std::less<ranges::range_value_t<R>>, Alloc>;

1-4) These deduction guides are provided for set to allow deduction from an iterator
range (overloads (1,3)) and std::initializer_list (overloads (2,4)).
5,6) These deduction guides are provided for set to allow deduction from a
std::from_range_t tag and an input_range.

These overloads participate in overload resolution only if InputIt satisfies
LegacyInputIterator, Alloc satisfies Allocator, and Comp does not satisfy Allocator.

Note: the extent to which the library determines that a type does not satisfy
LegacyInputIterator is unspecified, except that as a minimum integral types do not
qualify as input iterators. Likewise, the extent to which it determines that a type
does not satisfy Allocator is unspecified, except that as a minimum the member type
Alloc::value_type must exist and the expression
std::declval<Alloc&>().allocate(std::size_t{}) must be well-formed when treated as
an unevaluated operand.

Notes¶

Feature-test macro Value Std Feature
__cpp_lib_containers_ranges 202202L (C++23) Ranges-aware construction and insertion;
overload (5,6)

Example¶

// Run this code

#include <set>

int main()
{
// guide #2 deduces std::set<int>
std::set s = {1, 2, 3, 4};

// guide #1 deduces std::set<int>
std::set s2(s.begin(), s.end());
}