std::from_range, std::from_range_t
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C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Ranges library
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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.
[edit] Standard library
The following standard library types use std::from_range_t type in their constructors:
Containers library
(C++23)
vector from a range (public member function of
std::vector<T,Allocator>)
(C++26)
inplace_vector from a range (public member function of
std::inplace_vector<T,N>)
(C++26)
hive from a range (public member function of
Template:cpp/container/hive/title )
(C++23)
deque from a range (public member function of
std::deque<T,Allocator>)
(C++23)
forward_list from a range (public member function of
std::forward_list<T,Allocator>)
(C++23)
list from a range (public member function of
std::list<T,Allocator>)
(C++23)
set from a range (public member function of
std::set<Key,Compare,Allocator>)
(C++23)
map from a range (public member function of
std::map<Key,T,Compare,Allocator>)
(C++23)
multiset from a range (public member function of
std::multiset<Key,Compare,Allocator>)
(C++23)
multimap from a range (public member function of
std::multimap<Key,T,Compare,Allocator>)
(C++23)
unordered_set from a range (public member function of
std::unordered_set<Key,Hash,KeyEqual,Allocator>)
(C++23)
unordered_map from a range (public member function of
std::unordered_map<Key,T,Hash,KeyEqual,Allocator>)
(C++23)
unordered_multiset from a range (public member function of
std::unordered_multiset<Key,Hash,KeyEqual,Allocator>)
(C++23)
unordered_multimap from a range (public member function of
std::unordered_multimap<Key,T,Hash,KeyEqual,Allocator>)
(C++23)
priority_queue from a range (public member function of
std::priority_queue<T,Container,Compare>)
(C++23)
queue from a range (public member function of
std::queue<T,Container>)
(C++23)
stack from a range (public member function of
std::stack<T,Container>)
(C++23)
flat_set from a range (public member function of
std::flat_set<Key,Compare,KeyContainer>)
(C++23)
flat_map from a range (public member function of
std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>)
(C++23)
flat_multiset from a range (public member function of
std::flat_multiset<Key,Compare,KeyContainer>)
(C++23)
flat_multimap from a range (public member function of
std::flat_multimap<Key,T,Compare,KeyContainer,MappedContainer>)
Strings library
(C++23)
basic_string from a range (public member function of
std::basic_string<CharT,Traits,Allocator>)
[edit] Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_containers_ranges |
202202L |
(C++23) | Tagged constructors to construct from container compatible range |
[edit] 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 }