Difference between revisions of "cpp/container/span/last"
From cppreference.com
(Being pedantic as size_type is necessarily std::size_t. But for the second version the standard uses size_type and not explicitly std::size_t) |
m (langlinks) |
||
| Line 59: | Line 59: | ||
{{dsc end}} | {{dsc end}} | ||
| − | {{langlinks|ja|zh}} | + | {{langlinks|de|es|ja|ru|zh}} |
Revision as of 12:46, 20 November 2021
| template< std::size_t Count > constexpr std::span<element_type, Count> last() const; |
||
| constexpr std::span<element_type, std::dynamic_extent> last( size_type Count ) const; |
||
Obtains a span that is a view over the last Count elements of this span. The program is ill-formed if Count > Extent. The behavior is undefined if Count > size().
Return value
A span r that is a view over the last Count elements of *this, such that r.data() == this->data() + (this->size() - Count) && r.size() == Count.
Run this code
#include <iostream> #include <span> #include <string_view> auto print = [](std::string_view const title, auto const& container) { std::cout << title << "[" << std::size(container) << "]{ "; for (auto const& elem : container) std::cout << elem << ", "; std::cout << "};\n"; }; void run(std::span<const int> span) { print("span: ", span); std::span<const int, 3> span_last = span.last<3>(); print("span.last<3>(): ", span_last); std::span<const int, std::dynamic_extent> span_last_dynamic = span.last(2); print("span.last(2): ", span_last_dynamic); } int main() { int a[8]{ 1, 2, 3, 4, 5, 6, 7, 8, }; print("int a", a); run(a); }
Output:
int a[8]{ 1, 2, 3, 4, 5, 6, 7, 8, };
span: [8]{ 1, 2, 3, 4, 5, 6, 7, 8, };
span.last<3>(): [3]{ 6, 7, 8, };
span.last(2): [2]{ 7, 8, };See also
obtains a subspan consisting of the first N elements of the sequence (public member function) | |
| obtains a subspan (public member function) |
