std::return_temporary_buffer

 

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Defined in header <memory>
template< class T > void return_temporary_buffer( T* p );		(deprecated in C++17) (removed in C++20)

Deallocates the storage referenced by p.

If p is not a pointer value returned by an earlier call to std::get_temporary_buffer, or has been invalidated by an intervening std::return_temporary_buffer call, the behavior is undefined.

Parameters

p

-

the pointer referring to the storage to be declloated

Return value

(none)

Exceptions

Throws nothing.

Example

Run this code

#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...

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 2072	C++98	the storage allocated by std::get_temporary_buffer could be deallocated multiple times	the behavior is undefined in this case

See also

get_temporary_buffer (deprecated in C++17)(removed in C++20)

obtains uninitialized storage (function template)