std::uninitialized_fill_n

From cppreference.com

Defined in header `<memory>`

template< class ForwardIt, class Size, class T > void uninitialized_fill_n( ForwardIt first, Size count, const T& value )

Copies the given value value to the first count elements in an uninitialized memory area beginning at first. The elements in the uninitialized area are constructed using copy constructor.

template< class ForwardIt, class Size, class T >
void uninitialized_fill_n(ForwardIt first, Size count
                          const T& value)
{
    typedef typename std::iterator_traits<ForwardIt>::value_type Value;
    for (; count > 0; ++first, --count) {
        ::new (static_cast<void*>(&*first)) Value(value);
    }
    return first;
}

[edit] Example

run this code

#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

[edit] See also


uninitialized_fill	copies an object to an uninitialized area of memory (function template)

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)

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`.

std::uninitialized_fill_n

Contents

[edit] Parameters

[edit] Return value

[edit] Complexity

[edit] Possible implementation

[edit] Example

[edit] See also