If count is negative or zero, does nothing.
Otherwise, requests to allocate uninitialized contiguous storage for count adjacent objects of type T. The request is non-binding, and the implementation may instead allocate the storage for any other number of (including zero) adjacent objects of type T.
It is implementation-defined whether over-aligned types are supported.
(since C++11) [edit] Parameters count - the desired number of objects [edit] Return valueA std::pair, the member first is a pointer to the beginning of the allocated storage and the member second is the number of objects that fit in the storage that was actually allocated.
If count <= 0 or allocated storage is not enough to store a single element of type T, the member first of the result is a null pointer and the member second is zero.
This API was originally designed with the intent of providing a more efficient implementation than the general-purpose operator new, but no such implementation was created and the API was deprecated and removed.
[edit] Example#include <algorithm>
#include <iostream>
#include <iterator>
#include <memory>
#include <string>
int main()
{
const std::string s[] = {"string", "1", "test", "..."};
const auto p = std::get_temporary_buffer<std::string>(4);
// requires that p.first is passed to return_temporary_buffer
// (beware of early exit points and exceptions), or better use:
std::unique_ptr<std::string, void(*)(std::string*)> on_exit(p.first,
[](std::string* p)
{
std::cout << "returning temporary buffer...\n";
std::return_temporary_buffer(p);
});
std::copy(s, s + p.second,
std::raw_storage_iterator<std::string*, std::string>(p.first));
// has same effect as: std::uninitialized_copy(s, s + p.second, p.first);
// requires that each string in p is individually destroyed
// (beware of early exit points and exceptions)
std::copy(p.first, p.first + p.second,
std::ostream_iterator<std::string>{std::cout, "\n"});
std::for_each(p.first, p.first + p.second, [](std::string& e)
{
e.~basic_string<char>();
}); // same as: std::destroy(p.first, p.first + p.second);
// manually reclaim memory if unique_ptr-like technique is not used:
// std::return_temporary_buffer(p.first);
}
Output:
string 1 test ... returning temporary buffer...[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior LWG 425 C++98 the behavior when count <= 0 was unclear made clear LWG 2072 C++98 it was not allowed to allocate insufficient memory allowed [edit] See also(deprecated in C++17)(removed in C++20)
frees uninitialized storagestd::allocator_traits<Alloc>) [edit]
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