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uninitialized_fill_n
function template
<memory>
template <class ForwardIterator, class Size, class T>
void uninitialized_fill (ForwardIterator first, Size n, const T& x);
Fill block of memory
Constructs n elements in the array pointed by first, initializing them to a value of x.
Unlike algorithm fill_n, uninitialized_fill_n constructs the objects at destination, instead of just copying the value to them. This allows to obtain fully constructed copies 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 ForwardIterator, class Size, class T >
void fill ( ForwardIterator first, Size n, const T& x )
{
for (; n--; ++first)
new (static_cast<void*>(&*first))
typename iterator_traits<ForwardIterator>::value_type(x);
}
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Parameters
- first
- Forward iterators to the initial position in an uninitialized sequence of at least n elements.
- n
- Number of elements to initialize
Size is expected to be a numeric type.
- x
- Value to be used to fill the range.
Return value
none
Example
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// uninitialized_fill_n example
#include <iostream>
#include <memory>
#include <string>
using namespace std;
int main () {
// get block of uninitialized memory:
pair <string*,ptrdiff_t> result = get_temporary_buffer<string>(3);
if (result.second>0) {
uninitialized_fill_n ( result.first, result.second, "c++ rocks!" );
for (int i=0; i<result.second; i++)
cout << result.first[i] << "\n";
return_temporary_buffer(result.first);
}
return 0;
}
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Output:
c++ rocks!
c++ rocks!
c++ rocks!
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Complexity
Linear: Constructs (copy constructor) as many objects as the number of elements in the range [first,last).
See also
| fill_n | Fill sequence with value (function template) |
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