public member function
<deque>

std::deque::emplace_back

template <class... Args>
  void emplace_back (Args&&... args);
Construct and insert element at the end
Inserts a new element at the end of the deque, right after its current last element. This new element is constructed in place using args as the arguments for its construction.

This effectively increases the container size by one.

The element is constructed in-place by calling allocator_traits::construct with args forwarded.

A similar member function exists, push_back, which either copies or moves an existing object into the container.

Parameters

args
Arguments forwarded to construct the new element.

Return value

none.

The storage for the new element is allocated using allocator_traits<allocator_type>::construct(), which may throw exceptions on failure (for the default allocator, bad_alloc is thrown if the allocation request does not succeed).

Example

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

int main ()
{
  std::deque<int> mydeque = {10,20,30};

  mydeque.emplace_back (100);
  mydeque.emplace_back (200);

  std::cout << "mydeque contains:";
  for (auto& x: mydeque)
    std::cout << ' ' << x;
  std::cout << '\n';

  return 0;
}

Output:
mydeque contains: 10 20 30 100 200

Complexity

Constant.

Iterator validity

All iterators related to this container are invalidated, but pointers and references remain valid, referring to the same elements they were referring to before the call.

Data races

The container is modified.
No contained elements are accessed by the call: concurrently accessing or modifying them is safe (although see iterator validity above).

Exception safety

Strong guarantee: if an exception is thrown, there are no changes in the container.
If allocator_traits::construct is not supported with the appropriate arguments, it causes undefined behavior.

See also

  • 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
  • 3038041528 2018-02-19
  • 9566341527 2018-02-19
  • 3936031526 2018-02-19
  • 9531111525 2018-02-19
  • 291211524 2018-02-19
  • 8962001523 2018-02-19