std::span back() method

since C++20

constexpr reference back() const;

Returns a reference

to the last character in the span.

Undefined Behavior

Calling back() on an empty span is undefined behavior

.

Parameters

(none)

Return value

Reference to the last element.

Complexity

Constant - O(1).

Notes

For a span s, the expression s.back() is equivalent to *std::prev(s.end()) and s[s.size() - 1].

Example

Main.cpp

#include <span>
#include <iostream>
 
int main() {
    for (std::span str{"ABCDEF"}; !str.empty(); str.remove_suffix(1))
        std::cout << str.back() << ' ' << str << '\n';
}

Output

F ABCDEF
E ABCDE
D ABCD
C ABC
B AB
A A