template< std::size_t Count >
constexpr std::span<element_type, Count>
last() const;
| (1) | (since C++20) |
constexpr std::span<element_type, std::dynamic_extent>
last( size_type Count ) const;
| (2) | (since C++20) |
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().
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.
#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, };|
(C++20) | obtains a subspan consisting of the first N elements of the sequence (public member function) |
|
(C++20) | obtains a subspan (public member function) |
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