std::raw_storage_iterator

 

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std::raw_storage_iterator

Member functions

raw_storage_iterator::raw_storage_iterator

raw_storage_iterator::operator=

raw_storage_iterator::operator*

raw_storage_iterator::base (C++17)

raw_storage_iterator::operator++raw_storage_iterator::operator++(int)

 

Defined in header <memory>
template<class OutputIt, class T > class raw_storage_iterator     :publicstd::iterator<std::output_iterator_tag, void, void, void, void>;		(until C++17)
template<class OutputIt, class T > class raw_storage_iterator;		(since C++17) (deprecated in C++17) (removed in C++20)

The output iterator std::raw_storage_iterator makes it possible for standard algorithms to store results in uninitialized memory. Whenever the algorithm writes an object of type T to the dereferenced iterator, the object is copy-constructed into the location in the uninitialized storage pointed to by the iterator. The template parameter OutputIt is any type that meets the requirements of LegacyOutputIterator and has operator* defined to return an object, for which operator& returns an object of type T*. Usually, the type T* is used as OutputIt.

Type requirements

- OutputIt must meet the requirements of LegacyOutputIterator.

Member functions

(constructor)	creates a new raw_storage_iterator (public member function)
operator=	constructs an object at the pointed-to location in the buffer (public member function)
operator*	dereferences the iterator (public member function)
operator++operator++(int)	advances the iterator (public member function)
base (since C++17)	provides access to the wrapped iterator (public member function)

Member types

Member type	Definition
iterator_category	std::output_iterator_tag
value_type	void
difference_type	void (until C++20) std::ptrdiff_t (since C++20)
pointer	void
reference	void

Member types iterator_category, value_type, difference_type, pointer and reference are required to be obtained by inheriting from std::iterator<std::output_iterator_tag, void, void, void, void>.

(until C++17)

Note

std::raw_storage_iterator was deprecated primarily because of its exception-unsafe behavior. Unlike std::uninitialized_copy, it doesn't handle exceptions during operations like std::copy safely, potentially leading to resource leaks due to a lack of tracking the number of successfully constructed objects and their proper destruction in the presence of exceptions.

Example

Run this code

#include <algorithm>#include <iostream>#include <memory>#include <string>   int main(){conststd::string s[]={"This", "is", "a", "test", "."};std::string* p =std::allocator<std::string>().allocate(5);   std::copy(std::begin(s), std::end(s), std::raw_storage_iterator<std::string*, std::string>(p));   for(std::string* i = p; i != p +5;++i){std::cout<<*i <<'\n'; i->~basic_string<char>();}std::allocator<std::string>().deallocate(p, 5);}

Output:

This is a test .

See also

allocator_traits (C++11)	provides information about allocator types (class template)
scoped_allocator_adaptor (C++11)	implements multi-level allocator for multi-level containers (class template)
uses_allocator (C++11)	checks if the specified type supports uses-allocator construction (class template)