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

 

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std::inplace_vector

Member types
Member functions
inplace_vector::inplace_vector inplace_vector::~inplace_vector    inplace_vector::operator= inplace_vector::assign inplace_vector::assign_range Size and capacity inplace_vector::empty inplace_vector::size inplace_vector::max_size inplace_vector::capacity inplace_vector::resize inplace_vector::reserve inplace_vector::shrink_to_fit Iterators inplace_vector::begininplace_vector::cbegin inplace_vector::endinplace_vector::cend inplace_vector::rbegininplace_vector::crbegin inplace_vector::rendinplace_vector::crend	Element access inplace_vector::at inplace_vector::operator[] inplace_vector::front inplace_vector::back inplace_vector::data Modifiers inplace_vector::clear inplace_vector::erase inplace_vector::swap inplace_vector::insert inplace_vector::insert_range inplace_vector::emplace inplace_vector::emplace_back inplace_vector::try_emplace_back inplace_vector::unchecked_emplace_back inplace_vector::push_back inplace_vector::try_push_back inplace_vector::unchecked_push_back inplace_vector::pop_back inplace_vector::append_range inplace_vector::try_append_range
Non-member functions
erase(std::inplace_vector)erase_if(std::inplace_vector) swap(std::inplace_vector)	operator==operator<=>

 

template< class... Args > constexpr iterator emplace( const_iterator position, Args&&... args );		(since C++26)

Inserts a new element into the container directly before pos. Typically, the element is constructed uses 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)....

Parameters

pos	-	iterator before which the new element will be constructed
args	-	arguments to forward to the constructor of the element
Type requirements
- T must meet the requirements of EmplaceConstructible.

Return value

An iterator to the inserted element.

Complexity

Linear: the distance between pos and end of the container + 1.

Exceptions

• Throws std::bad_alloc if before the invocation size() == capacity(). The function has no effects (strong exception safety guarantee).
• Any exception thrown by initialization of inserted element or by any LegacyInputIterator operation. Elements in [​0​, pos) are not modified.

Example

Run this code

#include <cassert>
#include <inplace_vector>
#include <new>
#include <utility>
 
int main()
{
    using P = std::pair<int, int>;
    using I = std::inplace_vector<P, 3>;
    auto nums = I{{0, 1}, {2, 3}};
 
    auto it = nums.emplace(nums.begin() + 1, -1, -2);
    assert((*it == P{-1, -2}));
    assert((nums == I{P{0, 1}, {-1, -2}, {2, 3}}));
 
    try
    {
        nums.emplace(nums.begin(), 1, 3); // throws: no space
    }
    catch(const std::bad_alloc& ex)
    {
        std::cout << ex.what() << '\n';
    }
}

Possible output:

std::bad_alloc

See also

insert	inserts elements (public member function)
emplace_back	constructs an element in-place at the end (public member function)