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std::ranges::drop_view<V>::drop_view

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< cpp‎ | ranges‎ | drop view
 
 
Ranges library
Range access
Range conversions
(C++23)

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(until C++23)(C++23)


 
 
drop_view() requires std::default_initializable<V> = default;
(1) (since C++20)
constexpr explicit drop_view( V base, ranges::range_difference_t<V> count );
(2) (since C++20)

Constructs a drop_view.

1) Default constructor. Value-initializes the underlying view and initializes the count to 0. After construction, base() returns a copy of V() and size() equals to the size of the underlying view.
2) Initializes the underlying view with std::move(base) and the count with count. After construction, base() returns a copy of base and size() returns ranges::size(base) - count if the size of base is not less than count, or 0 otherwise.

[edit] Parameters

base - the underlying view
count - number of elements to skip

[edit] Example

#include <algorithm>
#include <array>
#include <iostream>
#include <iterator>
#include <ranges>
 
int main()
{
    constexpr std::array hi{'H', 'e', 'l', 'l', 'o', ',',
                            ' ', 'C', '+', '+', '2', '0'};
 
    std::ranges::for_each(hi, [](const char c){ std::cout << c; });
    std::cout << '\n';
 
    constexpr auto n = std::distance(hi.cbegin(), std::ranges::find(hi, 'C'));
 
    auto cxx = std::ranges::drop_view{hi, n};
 
    std::ranges::for_each(cxx, [](const char c){ std::cout << c; });
    std::cout << '\n';
}

Output:

Hello, C++20
C++20

[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 3714
(P2711R1)
C++20 the multi-parameter constructor was not explicit made explicit