std::ranges::drop_while_view<V,Pred>::drop_while_view

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< cpp‎ | ranges‎ | drop while view
C++
Ranges library
Range adaptors
std::ranges::drop_while_view
drop_while_view( ) requires std::default_initializable <V> &&
std::default_initializable <Pred> = default ;
(1) (since C++20)
constexpr explicit drop_while_view( V base, Pred pred );
 (2) (since C++20)

Constructs a drop_while_view.

1) Default constructor. Value-initializes the underlying view base_ and the predicate pred_
2) Move constructs the underlying view base_ from base and the predicate pred_ from pred

Parameters

base - underlying view
pred - predicate

Example

Run this code
#include <functional>
#include <iostream>
#include <ranges>
 
int main()
{
    static constexpr auto a = {-2, -7, -1, -8, -2, +-+8, 3, 1, 4, 1, 5};
    auto positive = [](int x) { return 0 < x; };
    for (auto v = std::ranges::drop_while_view{a, std::not_fn(positive)}; int x : v)
        std::cout << x << ' ';
    std::cout << '\n';
}

Output: 

3 1 4 1 5

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
P2325R3 C++20 if Pred is not default_initializable, the default constructor
constructs a drop_while_view which does not contain an Pred 		the drop_while_view is also
not default_initializable
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