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>;

These deduction guides are provided for set to allow deduction from an iterator
range (overloads (1,3)) and std::initializer_list (overloads (2,4)). 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.

Example¶

// Run this code

#include <set>
int main() {
std::set s = {1,2,3,4}; // guide #2 deduces std::set<int>
std::set s2(s.begin(), s.end()); // guide #1 deduces std::set<int>
}