std::uninitialized_fill

 

C++

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)

Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)

Dynamic memory management

Error handling

Program utilities

Variadic functions

Date and time

Function objects

initializer_list (C++11)

bitset

hash (C++11)

Relational operators

rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=

Pairs and tuples

pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

integer_sequence (C++14)

Swap, forward and move

swap

exchange (C++14)

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

declval (C++11)

 

Dynamic memory management

Smart pointers
unique_ptr (C++11)
shared_ptr (C++11)
weak_ptr (C++11)
auto_ptr (until C++17)
owner_less (C++11)
enable_shared_from_this (C++11)
bad_weak_ptr (C++11)
default_delete (C++11)
Allocators
allocator
allocator_traits (C++11)
allocator_arg_t (C++11)
allocator_arg (C++11)
uses_allocator (C++11)
scoped_allocator_adaptor (C++11)
Uninitialized storage
uninitialized_copy
uninitialized_copy_n (C++11)
uninitialized_fill
uninitialized_fill_n
raw_storage_iterator
get_temporary_buffer
return_temporary_buffer
Garbage collection support
declare_reachable (C++11)
undeclare_reachable (C++11)
declare_no_pointers (C++11)
undeclare_no_pointers (C++11)
pointer_safety (C++11)
get_pointer_safety (C++11)
Miscellaneous
pointer_traits (C++11)
addressof (C++11)
align (C++11)
C Library
malloc calloc	realloc free
Low level memory management

 

Defined in header <memory>
template< class ForwardIt, class T > void uninitialized_fill( ForwardIt first, ForwardIt last, const T& value );

Copies the given value to an uninitialized memory area, defined by the range [first, last) as if by

for (; first != last; ++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, last	-	the range of the elements to initialize
value	-	the value to construct the elements with
Type requirements
- ForwardIt must meet the requirements of ForwardIterator.

Return value

(none)

Complexity

Linear in the distance between first and last

Possible implementation

template<class ForwardIt, class T> void uninitialized_fill(ForwardIt first, ForwardIt last, const T& value) { typedef typename std::iterator_traits<ForwardIt>::value_type Value; ForwardIt current = first; try { for (; current != last; ++current) { ::new (static_cast<void*>(std::addressof(*current))) Value(value); } } catch (...) { for (; first != current; ++first) { first->~Value(); } throw; } }

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(p, 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

uninitialized_fill_n	copies an object to an uninitialized area of memory (function template)
std::experimental::parallel::uninitialized_fill (parallelism TS)	parallelized version of std::uninitialized_fill (function template)