NAME

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

Synopsis

constexpr reference back() const;

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 <span>
#include <iostream>

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