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std::span<T,Extent>::back

From cppreference.com
< cpp‎ | container‎ | span
 
 
 
 
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.

Contents

[edit] Parameters

(none)

[edit] Return value

A reference to the back element.

[edit] Complexity

Constant.

[edit] Notes

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

[edit] Example

#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

[edit] See also

(C++20)
access the first element
(public member function) [edit]