NAME¶

std::from_range,std::from_range_t - std::from_range,std::from_range_t

Synopsis¶

Defined in header <ranges>
struct from_range_t { explicit from_range_t() = default; }; (since C++23)
inline constexpr std::from_range_t from_range {}; (since C++23)

std::from_range is a disambiguation tag that can be passed to the constructors of
the suitable containers to indicate that the contained member is range constructed.

The corresponding type std::from_range_t can be used in the constructor's parameter
list to match the intended tag.

Standard library¶

The following standard library types use std::from_range_t type in their
constructors:

Containers library¶

constructor constructs the vector from a range
(C++23) (public member function of std::vector<T,Allocator>)
constructor constructs the deque from a range
(C++23) (public member function of std::deque<T,Allocator>)
constructor constructs the forward_list from a range
(C++23) (public member function of std::forward_list<T,Allocator>)
constructor constructs the list from a range
(C++23) (public member function of std::list<T,Allocator>)
constructor constructs the set from a range
(C++23) (public member function of std::set<Key,Compare,Allocator>)
constructor constructs the map from a range
(C++23) (public member function of std::map<Key,T,Compare,Allocator>)
constructor constructs the multiset from a range
(C++23) (public member function of std::multiset<Key,Compare,Allocator>)
constructor constructs the multimap from a range
(C++23) (public member function of std::multimap<Key,T,Compare,Allocator>)
constructor constructs the unordered_set from a range
(C++23) (public member function of
std::unordered_set<Key,Hash,KeyEqual,Allocator>)
constructor constructs the unordered_map from a range
(C++23) (public member function of
std::unordered_map<Key,T,Hash,KeyEqual,Allocator>)
constructor constructs the unordered_multiset from a range
(C++23) (public member function of
std::unordered_multiset<Key,Hash,KeyEqual,Allocator>)
constructor constructs the unordered_multimap from a range
(C++23) (public member function of
std::unordered_multimap<Key,T,Hash,KeyEqual,Allocator>)
constructor constructs the priority_queue from a range
(C++23) (public member function of std::priority_queue<T,Container,Compare>)
constructor constructs the queue from a range
(C++23) (public member function of std::queue<T,Container>)
constructor constructs the stack from a range
(C++23) (public member function of std::stack<T,Container>)
constructor constructs the flat_set from a range
(C++23) (public member function of std::flat_set<Key,Compare,KeyContainer>)
constructor constructs the flat_map from a range
(C++23) (public member function of
std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>)
constructor constructs the flat_multiset from a range
(C++23) (public member function of
std::flat_multiset<Key,Compare,KeyContainer>)
constructor constructs the flat_multimap from a range
(C++23) (public member function of
std::flat_multimap<Key,T,Compare,KeyContainer,MappedContainer>)

Strings library¶

constructor constructs the basic_string from a range
(C++23) (public member function of std::basic_string<CharT,Traits,Allocator>)

Notes¶

Feature-test macro Value Std Feature
__cpp_lib_containers_ranges 202202L (C++23) Tagged constructors to construct from
container compatible range

Example¶

// Run this code

#include <cassert>
#include <string>

int main()
{
#ifdef __cpp_lib_containers_ranges
auto const range = {0x43, 43, 43};
std::string str{std::from_range, range}; // uses tagged constructor
assert(str == "C++");
#endif
}

See also¶

in_place
in_place_type
in_place_index in-place construction tag
in_place_t (tag)
in_place_type_t
in_place_index_t
(C++17)
sorted_equivalent indicates that elements of a range are sorted (uniqueness is not
sorted_equivalent_t required)
(C++23) (tag)
sorted_unique indicates that elements of a range are sorted and unique
sorted_unique_t (tag)
(C++23)
ranges::to constructs a new non-view object from an input range
(C++23) (function template)