NAME¶

std::span::last - std::span::last

Synopsis¶

template< std::size_t Count > (1) (since C++20)
constexpr std::span<element_type, Count> last() const;
constexpr std::span<element_type, std::dynamic_extent> last( (2) (since C++20)
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.

Example¶

// Run this code

#include <iostream>
#include <span>
#include <string_view>

void println(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)
{
println("span: ", span);

std::span<const int, 3> span_last = span.last<3>();
println("span.last<3>(): ", span_last);

std::span<const int, std::dynamic_extent> span_last_dynamic = span.last(2);
println("span.last(2): ", span_last_dynamic);
}

int main()
{
int a[8]{1, 2, 3, 4, 5, 6, 7, 8};
println("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¶

first obtains a subspan consisting of the first N elements of the sequence
(public member function)
subspan obtains a subspan
(public member function)