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Defined in header <ranges> | ||
inlineconstexpr/* unspecified */ all=/* unspecified */; | (1) | (since C++20) |
template<ranges::viewable_range R> using all_t= decltype(views::all(std::declval<R>())); | (2) | (since C++20) |
view that includes all elements of itsrange argument.R, the expressionviews::all(e) isexpression-equivalent to:view, implicitly convertinge to astd::decay_t<R> prvalue.#include <iostream>#include <ranges>#include <type_traits>#include <vector> int main(){std::vector<int> v{0,1,2,3,4,5};for(int n: std::views::all(v)| std::views::take(2))std::cout<< n<<' ';std::cout<<'\n'; static_assert(std::is_same< decltype(std::views::single(42)), std::ranges::single_view<int>>{}); static_assert(std::is_same< decltype(std::views::all(v)), std::ranges::ref_view<std::vector<int,std::allocator<int>>>>{}); int a[]{1,2,3,4}; static_assert(std::is_same< decltype(std::views::all(a)), std::ranges::ref_view<int[4]>>{}); static_assert(std::is_same< decltype(std::ranges::subrange{std::begin(a)+1,std::end(a)-1}), std::ranges::subrange<int*,int*, std::ranges::subrange_kind(1)>>{});}
Output:
0 1
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 3724 | C++20 | views::all might result in hard error for some move-only views | it gets well-constrained |
| P2415R2 | C++20 | views::all returned asubrange for a non-view rvaluerange | returns anowning_view for it |
an emptyview with no elements(class template)(variable template)[edit] | |
aview that contains a single element of a specified value(class template)(customization point object)[edit] | |
(C++20) | aview with unique ownership of somerange(class template)[edit] |
