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

 

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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 pointer try_emplace_back( Args&&... args );		(since C++26)

Conditionally appends an object of type T to the end of the container.

If size() == capacity() is true, there are no effects. Otherwise, appends direct-non-list-initialized with std::forward<Args>(args)... object of type T.

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 be EmplaceConstructible into inplace_vector from std::forward<Args>(args)....

Return value

std::addressof(back()) if size() < capacity(), nullptr otherwise.

Complexity

Constant.

Exceptions

Any exception thrown by initialization of inserted element. If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

Example

Run this code

#include <cassert>
#include <complex>
#include <inplace_vector>
 
int main()
{
    using namespace std::complex_literals;
    using C = std::complex<double>;
    using I = std::inplace_vector<C, 3>;
    auto v = I{1.0 + 2.0i, 3.0 + 4.0i};
 
    C* c = v.try_emplace_back(5.0, 6.0);
    assert(*c == 5.0 + 6.0i);
    assert((v == I{1.0 + 2.0i, 3.0 + 4.0i, 5.0 + 6.0i}));
 
    c = v.try_emplace_back(7.0, 8.0); // no space => no insertion
    assert(c == nullptr);
    assert((v == I{1.0 + 2.0i, 3.0 + 4.0i, 5.0 + 6.0i}));
}

See also

emplace_back	constructs an element in-place at the end (public member function)
push_back	adds an element to the end (public member function)
append_range	adds a range of elements to the end (public member function)
try_append_range	tries to add a range of elements to the end (public member function)
unchecked_emplace_back	unconditionally constructs an element in-place at the end (public member function)
unchecked_push_back	unconditionally adds an element to the end (public member function)
pop_back	removes the last element (public member function)
back_inserter	creates a std::back_insert_iterator of type inferred from the argument (function template)