std::uninitialized_fill

`<memory>`
`template< class ForwardIt, class T > void uninitialized_fill( ForwardIt first, ForwardIt last, const T& value );`	(1)
`template< class ExecutionPolicy, class ForwardIt, class T > void uninitialized_fill( ExecutionPolicy&& policy, ForwardIt first, ForwardIt last, const T& value );`	(2)	( C++17)

1) value , [first, last),

for (; first != last; ++first)
::new (/*VOIDIFY*/(*first))
typename std::iterator_traits<ForwardIt>::value_type(value);

/* VOIDIFY */(e) :

`static_cast<void*>(&e)`	( C++11)
`static_cast<void*>(std::addressof(e))`	( C++11)

, .

2) , (1), policy. ,

`std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>` `true`.	( C++20)
`std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>` `true`.	( C++20)

first, last
value		,
policy		. .

- `ForwardIt` LegacyForwardIterator.
- , , `ForwardIt` . `&*` `ForwardIt` . ( C++11)

()

first last.

ExecutionPolicy :

, , ExecutionPolicy , std::terminate. ExecutionPolicy .
, std::bad_alloc.

template<class ForwardIt, class T>
void uninitialized_fill(ForwardIt first, ForwardIt last, const T& value)
{
    using V = typename std::iterator_traits<ForwardIt>::value_type;
    ForwardIt current = first;
    try
    {
        for (; current != last; ++current)
            ::new (static_cast<void*>(std::addressof(*current))) V(value);
    } 
    catch (...)
    {
        for (; first != current; ++first)
            first->~V();
        throw;
    }
}

#include <algorithm>
#include <iostream>
#include <memory>
#include <string>

int main()
{
    const std::size_t sz = 4;
    std::allocator<std::string> alloc;
    std::string* p = alloc.allocate(sz);

    std::uninitialized_fill(p, p + sz, "");

    for (std::string* i = p; i != p + sz; ++i)
    {
        std::cout << *i << '\n';
        i->~basic_string<char>();
    }

    alloc.deallocate(p, sz);
}

:

C++:


LWG 866	C++98	`T` `ForwardIt`, `T::operator new` ,	-new
LWG 2433	C++11	`operator&`	std::addressof
LWG 3870	C++20	`const`

uninitialized_fill_n	, ( ) []
ranges::uninitialized_fill (C++20)	, () []







(C++20)

(C++20)
(C++11)





(C++20)


/

(C++11)
(C++11)
(C++11)
(C++17)

cppreference.com

std::uninitialized_fill