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);
}


Parameters

first
Forward iterators to the initial position in an unitialized 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;
}


Output:
c++ rocks!
c++ rocks!
c++ rocks!


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)
uninitialized_copy Copy block of memory (function template)
uninitialized_fill Fill block of memory (function template)
get_temporary_buffer Get block of temporary memory (function template)