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/C++

std::vector<T,Allocator>::back

	(1)
reference back();		(until C++20)
constexpr reference back();		(since C++20)
	(2)
const_reference back() const;		(until C++20)
constexpr const_reference back() const;		(since C++20)

Returns a reference to the last element in the container.

Calling back on an empty container causes undefined behavior.

Parameters

(none).

Return value

Reference to the last element.

Complexity

Constant.

Notes

For a non-empty container c, the expression c.back() is equivalent to *std::prev(c.end()).

Example

The following code uses back to display the last element of a std::vector<char>:

#include <vector>
#include <iostream>
 
int main()
{
    std::vector<char> letters {'a', 'b', 'c', 'd', 'e', 'f'};
 
    if (!letters.empty())
        std::cout << "The last character is '" << letters.back() << "'.\n";
}

Output: