std::inplace_vector<T,N>::emplace_back
From cppreference.com
template< class... Args >
constexpr reference emplace_back( Args&&... args );
|
(since C++26) | |
Appends a new element to the end of the container. Typically, the element is constructed using placement-new to construct the element in-place at the location provided by the container. The arguments args... are forwarded to the constructor as std::forward<Args>(args)....
No iterators or references are invalidated, except end(), which is invalidated if the insertion occurs.
Parameters
| args | - | arguments to forward to the constructor of the element |
| Type requirements | ||
-T must meet the requirements of EmplaceConstructible.
| ||
Return value
back(), i.e. a reference to the inserted element.
Complexity
Constant.
Exceptions
- std::bad_alloc if
size() == capacity()before invocation. - Any exception thrown by initialization of the inserted element.
If an exception is thrown for any reason, these functions have no effect (strong exception safety guarantee).
Example
Run this code
#include <inplace_vector>
#include <new>
#include <print>
#include <string>
#include <utility>
int main()
{
std::inplace_vector<std::pair<std::string, std::string>, 2> fauna;
std::string dog{"\N{DOG}"};
fauna.emplace_back("\N{CAT}", dog);
fauna.emplace_back("\N{CAT}", std::move(dog));
std::println("fauna = {}", fauna);
try
{
fauna.emplace_back("\N{BUG}", "\N{BUG}"); // throws: there is no space
}
catch(const std::bad_alloc& ex)
{
std::println("{}", ex.what());
}
std::println("fauna = {}", fauna);
}
Possible output:
fauna = [("🐈", "🐕"), ("🐈", "🐕")]
std::bad_alloc
fauna = [("🐈", "🐕"), ("🐈", "🐕")]
See also
| adds a range of elements to the end (public member function) | |
| adds an element to the end (public member function) | |
| tries to add an element to the end (public member function) | |
| tries to construct an element in-place at the end (public member function) | |
| tries to add a range of elements to the end (public member function) | |
| unconditionally adds an element to the end (public member function) | |
| unconditionally constructs an element in-place at the end (public member function) | |
| removes the last element (public member function) | |
| creates a std::back_insert_iterator of type inferred from the argument (function template) |