inline constexpr /* unspecified */ drop = /* unspecified */;
Call signature
(since C++20)template< class DifferenceType >
constexpr /* range adaptor closure */ drop( DifferenceType&& count );
1) A range adaptor consisting of elements of the underlying sequence, skipping the first N elements.
2) RangeAdaptorObject. Given
T
is
std::remove_cvref_t<decltype((e))>and
D
is
ranges::range_difference_t<decltype((e))>), the expression
views::drop(e, f)is
expression-equivalentto:
decay-copy(e)), if T is a ranges::empty_view, except that the evaluations of e and f are indeterminately sequenced;T is a specialization of ranges::subrange that models both random_access_range and sized_range, and T needs to store the size (see ranges::subrange::subrange() for details), where inc is std::min<D>(ranges::distance(e), f);T is a specialization of std::span, std::basic_string_view, ranges::iota_view, or ranges::subrange that models both random_access_range and sized_range, where U isIn all cases,
decltype((f))must model
std::convertible_to<D>.
drop_view models the concepts contiguous_range, random_access_range, bidirectional_range, forward_range, input_range, common_range, and sized_range when the underlying view V models respective concepts.
drop_view
sized_range
approximately_sized_range
sized_range or forward_range
std::ranges::view_interface<D>) [edit] returns a constant iterator to the beginning of the range
std::ranges::view_interface<D>) [edit] returns a sentinel for the constant iterator of the range
std::ranges::view_interface<D>) [edit] returns whether the derived view is not empty, provided only if ranges::empty is applicable to it
std::ranges::view_interface<D>) [edit] gets the address of derived view's data, provided only if its iterator type satisfies contiguous_iterator
std::ranges::view_interface<D>) [edit] returns the first element in the derived view, provided if it satisfies forward_range
std::ranges::view_interface<D>) [edit] returns the last element in the derived view, provided only if it satisfies bidirectional_range and common_range
std::ranges::view_interface<D>) [edit] returns the nth element in the derived view, provided only if it satisfies random_access_range
std::ranges::view_interface<D>) [edit] [edit] Deduction guides [edit] Helper templates
This specialization of ranges::enable_borrowed_range makes drop_view satisfy borrowed_range when the underlying view satisfies it.
#include <initializer_list>
#include <iostream>
#include <ranges>
int main()
{
const auto nums = {1, 2, 3, 4, 5, 6, 7};
std::cout << "drop " << 2 << ": ";
for (int i : std::ranges::drop_view{nums, 2})
std::cout << i << ' ';
std::cout << '\n';
std::cout << "drop " << 3 << ": ";
for (int i : nums | std::views::drop(3))
std::cout << i << ' ';
std::cout << '\n';
std::cout << "drop " << 4 << ": ";
for (int i : std::views::iota(1, 8) | std::views::drop(4))
std::cout << i << ' ';
std::cout << '\n';
// Note that dropping more than the number of elements is OK:
for (int dp : {5, 6, 7, 890, 100500})
{
std::cout << "drop " << dp << ": ";
for (int i : std::views::iota(1, 8) | std::views::drop(dp))
std::cout << i << ' ';
std::cout << '\n';
}
}
Output:
drop 2: 3 4 5 6 7 drop 3: 4 5 6 7 drop 4: 5 6 7 drop 5: 6 7 drop 6: 7 drop 7: drop 890: drop 100500:[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior LWG 3407 C++20views::drop sometimes fails to
drop_view was never a borrowed_range it is a borrowed_range if its underlying view is [edit] See also
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4