std::get_temporary_buffer
From cppreference.com
| Defined in header <memory>
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| template< class T > std::pair< T*, std::ptrdiff_t > get_temporary_buffer( std::ptrdiff_t count ) |
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Allocates storage sufficient to store up to count adjacent objects of type T. If there is insufficient memory for all count objects, allocates less than count, if possible.
Contents |
Parameters
| count | - | the number of objects to allocate |
Return value
An std::pair holding a pointer to the beginning of the allocated storage and the number of objects that fit in the storage that was actually allocated (may be zero).
Exceptions
noexcept specification:
noexcept
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...
See also
| (deprecated in C++17)(removed in C++20) |
frees uninitialized storage (function template) |
