std::forward_list
Defined in header <forward_list> | ||
|---|---|---|
template< class InputIt,
class Alloc = std::allocator<
typename std::iterator_traits<InputIt>::value_type> >
forward_list( InputIt, InputIt, Alloc = Alloc() )
-> forward_list<typename std::iterator_traits<InputIt>::value_type, Alloc>;
| (1) | (since C++17) |
template< ranges::input_range R,
class Alloc = std::allocator<ranges::range_value_t<R>> >
forward_list( std::from_range_t, R&&, Alloc = Alloc() )
-> forward_list<ranges::range_value_t<R>, Alloc>;
| (2) | (since C++23) |
InputIt satisfies LegacyInputIterator and Alloc satisfies Allocator.std::from_range_t tag and an input_range.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.
| Feature-test macro | Value | Std | Comment |
|---|---|---|---|
__cpp_lib_containers_ranges | 202202L | (C++23) | Ranges-aware construction and insertion; overload (2) |
#include <forward_list>
#include <vector>
int main()
{
std::vector<int> v = {1, 2, 3, 4};
// uses explicit deduction guide to deduce std::forward_list<int>
std::forward_list x(v.begin(), v.end());
// deduces std::forward_list<std::vector<int>::iterator>
// first phase of overload resolution for list-initialization selects the candidate
// synthesized from the initializer-list constructor; second phase is not performed
// and deduction guide has no effect
std::forward_list y{v.begin(), v.end()};
}
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