NAME¶

std::span::back - std::span::back

Synopsis¶

constexpr reference back() const; (since C++20)

Returns a reference to the last element in the span.

Calling back on an empty span results in undefined behavior.

Parameters¶

(none)

Return value¶

A reference to the back element.

Complexity¶

Constant.

Notes¶

For a span c, the expression c.back() is equivalent to *(c.end() - 1).

Example¶

// Run this code

#include <iostream>
#include <span>

void print_forward(std::span<const int> const span)
{
for (auto n{span.size()}; n != 0; --n)
std::cout << span.last(n).front() << ' ';
std::cout << '\n';
}

void print_backward(std::span<const int> const span)
{
for (auto n{span.size()}; n != 0; --n)
std::cout << span.first(n).back() << ' ';
std::cout << '\n';
}

int main()
{
constexpr int numbers[]{0, 1, 2, 3, 4};
print_forward(numbers);
print_backward(numbers);
}

Output:¶

0 1 2 3 4
4 3 2 1 0

See also¶

front access the first element
(public member function)