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uninitialized_copy
function template
<memory>
template <class InputIterator, class ForwardIterator>
ForwardIterator
uninitialized_copy ( InputIterator first, InputIterator last,
ForwardIterator result );
Copy block of memory
Constructs copies of the elements in the range [first,last) into a range beginning at result and returns an iterator to the last element in the destination range.
Unlike algorithm copy, uninitialized_copy constructs the objects at destination, instead of just copying them. This allows to obtain fully constructed copies of the elements into a range of uninitialized memory, such as a memory block obtained by a call to get_temporary_buffer or malloc.
The behavior of this function template is equivalent to:
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template<class InputIterator, class OutputIterator>
OutputIterator copy ( InputIterator first, InputIterator last, OutputIterator result )
{
for (; first!=last; ++result, ++first)
new (static_cast<void*>(&*result))
typename iterator_traits<ForwardIterator>::value_type(*first);
return result;
}
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Parameters
- first, last
- Input iterators to the initial and final positions in a sequence to be copied. The range used is [first,last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.
- result
- Output iterator to the initial position in the uninitialized destination sequence. This shall not point to any element in the range [first,last).
Return value
An iterator to the last element of the destination sequence where elements have been copied. [standard is ambiguous]
Example
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// uninitialized_copy example
#include <iostream>
#include <memory>
#include <string>
using namespace std;
int main () {
string numbers[] ={"one","two","three"};
// get block of uninitialized memory:
pair <string*,ptrdiff_t> result = get_temporary_buffer<string>(3);
if (result.second>0) {
uninitialized_copy ( numbers, numbers+result.second, result.first );
for (int i=0; i<result.second; i++)
cout << result.first[i] << " ";
cout << endl;
return_temporary_buffer(result.first);
}
return 0;
}
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Output:
Complexity
Linear: constructs (copy construction) as many objects as the distance between first and last.
See also
| copy | Copy range of elements (function template) |
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