public member function
<deque>

std::deque::back

      reference back();
const_reference back() const;
Access last element
Returns a reference to the last element in the container.

Unlike member deque::end, which returns an iterator just past this element, this function returns a direct reference.

Calling this function on an empty container causes undefined behavior.

Parameters

none

Return value

A reference to the last element in the deque container.

If the deque object is const-qualified, the function returns a const_reference. Otherwise, it returns a reference.

Member types reference and const_reference are the reference types to the elements of the container (see deque member types).

Example

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// deque::back
#include <iostream>
#include <deque>

int main ()
{
  std::deque<int> mydeque;

  mydeque.push_back(10);

  while (mydeque.back() != 0)
    mydeque.push_back ( mydeque.back() -1 );

  std::cout << "mydeque contains:";

  for (std::deque<int>::iterator it = mydeque.begin(); it!=mydeque.end(); ++it)
    std::cout << ' ' << *it;

  std::cout << '\n';

  return 0;
}


Output:
mydeque contains: 10 9 8 7 6 5 4 3 2 1 0

Complexity

Constant.

Iterator validity

No changes.

Data races

The container is accessed (neither the const nor the non-const versions modify the container).
The last element is potentially accessed or modified by the caller. Concurrently accessing or modifying other elements is safe.

Exception safety

If the container is not empty, the function never throws exceptions (no-throw guarantee).
Otherwise, it causes undefined behavior.

See also

  • 997351548 2018-02-20
  • 903691547 2018-02-20
  • 9127171546 2018-02-20
  • 2234751545 2018-02-20
  • 1685381544 2018-02-20
  • 911091543 2018-02-20
  • 9281021542 2018-02-20
  • 632231541 2018-02-20
  • 9751491540 2018-02-20
  • 8333621539 2018-02-20
  • 995001538 2018-02-20
  • 6477441537 2018-02-20
  • 511981536 2018-02-19
  • 2072881535 2018-02-19
  • 6024461534 2018-02-19
  • 7594061533 2018-02-19
  • 9311341532 2018-02-19
  • 4928331531 2018-02-19
  • 38561530 2018-02-19
  • 7776611529 2018-02-19