A RetroSearch Logo

Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Search Query:

Showing content from https://cplusplus.com/reference/deque/deque/emplace_front/ below:

public member function

<deque>

std::deque::emplace_front 
template <class... Args>  void emplace_front (Args&&... args);

Construct and insert element at beginning

Inserts a new element at the beginning of the deque, right before its current first 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_front, 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 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
// deque::emplace_from
#include <iostream>
#include <deque>

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

  mydeque.emplace_front (111);
  mydeque.emplace_front (222);

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

  return 0;
}
Output: 
mydeque contains: 222 111 10 20 30


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 safetyStrong 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
deque::emplace_back
Construct and insert element at the end (public member function)
deque::push_front
Insert element at beginning (public member function)
deque::emplace
Construct and insert element (public member function)
deque::erase
Erase elements (public member function)
deque::assign
Assign container content (public member function)

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4