Defined in header <memory> | ||
---|---|---|
template< class ForwardIt, class Size, class T > void uninitialized_fill_n( ForwardIt first, Size count, const T& value ); | (until C++11) | |
template< class ForwardIt, class Size, class T > ForwardIt uninitialized_fill_n( ForwardIt first, Size count, const T& value ); | (since C++11) |
Copies the given value value
to the first count
elements in an uninitialized memory area beginning at first
as if by.
for (; n--; ++first) ::new (static_cast<void*>(std::addressof(*first))) typename iterator_traits<ForwardIterator>::value_type(x);
If an exception is thrown during the initialization, the function has no effects.
Parameters
first | - | the beginning of the range of the elements to initialize |
count | - | number of elements to construct |
value | - | the value to construct the elements with |
Type requirements | ||
- ForwardIt must meet the requirements of ForwardIterator . |
Return value
(none) | (until C++11) |
Iterator to the element past the last element copied. | (since C++11) |
Complexity
Linear in count
.
Possible implementation
template< class ForwardIt, class Size, class T > ForwardIt uninitialized_fill_n(ForwardIt first, Size count, const T& value) { typedef typename std::iterator_traits<ForwardIt>::value_type Value; ForwardIt current = first; try { for (; count > 0; ++current, (void) --count) { ::new (static_cast<void*>(std::addressof(*current))) Value(value); } return current; } catch (...) { for (; first != current; ++first) { first->~Value(); } throw; } } |
Example
#include <algorithm> #include <iostream> #include <memory> #include <string> #include <tuple> int main() { std::string* p; std::size_t sz; std::tie(p, sz) = std::get_temporary_buffer<std::string>(4); std::uninitialized_fill_n(p, sz, "Example"); for (std::string* i = p; i != p+sz; ++i) { std::cout << *i << '\n'; i->~basic_string<char>(); } std::return_temporary_buffer(p); }
Output:
Example Example Example Example
See also
copies an object to an uninitialized area of memory (function template) | |
std::experimental::parallel::uninitialised_fill_n
(parallelism TS) | parallelized version of std::uninitialised_fill_n (function template) |
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