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

reference back();
const_reference back() const;

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::deque<char>:

Run this code

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

Output:

The last character is 'f'.

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Technical specifications
Symbols index
External libraries

Sequence
array (C++11)
vector
deque
forward_list (C++11)
list
Associative
set
multiset
map
multimap
Unordered associative
unordered_set (C++11)
unordered_multiset (C++11)
unordered_map (C++11)
unordered_multimap (C++11)
Adaptors
stack
queue
priority_queue
Views
span (C++20)

Member functions
deque::deque
deque::~deque
deque::operator=
deque::assign
deque::get_allocator
Element access
deque::at
deque::operator[]
deque::front
deque::back
Iterators
deque::begindeque::cbegin (C++11)
deque::enddeque::cend (C++11)
deque::rbegindeque::crbegin (C++11)
deque::renddeque::crend (C++11)
Capacity
deque::empty
deque::size
deque::max_size
deque::shrink_to_fit
Modifiers
deque::clear
deque::insert
deque::emplace
deque::erase
deque::push_front
deque::emplace_front
deque::pop_front
deque::push_back
deque::emplace_back
deque::pop_back
deque::resize
deque::swap
Non-member functions
std::swap
eraseerase_if (C++20)(C++20)
operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
Deduction guides(C++17)