std::inplace_vector<T,N>:: emplace_back

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

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

#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);
}

fauna = [("🐈", "🐕"), ("🐈", "🐕")]
std::bad_alloc
fauna = [("🐈", "🐕"), ("🐈", "🐕")]

See also