< cpp‎ | memory
Utilities library
General utilities
Date and time
Function objects
Formatting library (C++20)
Relational operators (deprecated in C++20)
Integer comparison functions
Swap and type operations
Common vocabulary types
Elementary string conversions
Dynamic memory management
Smart pointers
(until C++17)
Memory resources
Uninitialized storage
Uninitialized memory algorithms
Constrained uninitialized memory algorithms
Garbage collection support
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
Low level memory management
Defined in header <memory>
template< class InputIt, class NoThrowForwardIt >

NoThrowForwardIt uninitialized_move( InputIt first, InputIt last,

                                     NoThrowForwardIt d_first );
(1) (since C++17)
template< class ExecutionPolicy, class ForwardIt, class NoThrowForwardIt >

NoThrowForwardIt uninitialized_move( ExecutionPolicy&& policy,
                                     ForwardIt first, ForwardIt last,

                                     NoThrowForwardIt d_first );
(2) (since C++17)
1) Moves elements from the range [first, last) to an uninitialized memory area beginning at d_first as if by
for (; first != last; ++d_first, (void) ++first)
   ::new (static_cast<void*>(std::addressof(*d_first)))
      typename std::iterator_traits<NoThrowForwardIt>::value_type(std::move(*first));
If an exception is thrown during the initialization, some objects in [first, last) are left in a valid but unspecified state, and the objects already constructed are destroyed in an unspecified order.
2) Same as (1), but executed according to policy. This overload does not participate in overload resolution unless

std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true.

(until C++20)

std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>> is true.

(since C++20)


[edit] Parameters

first, last - the range of the elements to move
d_first - the beginning of the destination range
policy - the execution policy to use. See execution policy for details.
Type requirements
InputIt must meet the requirements of LegacyInputIterator.
ForwardIt must meet the requirements of LegacyForwardIterator.
NoThrowForwardIt must meet the requirements of LegacyForwardIterator.
No increment, assignment, comparison, or indirection through valid instances of NoThrowForwardIt may throw exceptions.

[edit] Return value

Iterator to the element past the last element moved.

[edit] Complexity

Linear in the distance between first and last.

[edit] Exceptions

The overload with a template parameter named ExecutionPolicy reports errors as follows:

  • If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the standard policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
  • If the algorithm fails to allocate memory, std::bad_alloc is thrown.

[edit] Possible implementation

template<class InputIt, class NoThrowForwardIt>
NoThrowForwardIt uninitialized_move(InputIt first, InputIt last, NoThrowForwardIt d_first)
    using Value = typename std::iterator_traits<NoThrowForwardIt>::value_type;
    NoThrowForwardIt current = d_first;
    try {
        for (; first != last; ++first, (void) ++current) {
            ::new (static_cast<void*>(std::addressof(*current))) Value(std::move(*first));
        return current;
    } catch (...) {
        std::destroy(d_first, current);

[edit] Example

#include <cstdlib>
#include <iomanip>
#include <iostream>
#include <memory>
#include <string>
void print(auto rem, auto first, auto last) {
    for (std::cout << rem; first != last; ++first)
        std::cout << std::quoted(*first) << ' ';
    std::cout << '\n';
int main() {
    std::string in[] { "Home", "Work!" };
    print("initially, in: ", std::begin(in), std::end(in));
    if (
        constexpr auto sz = std::size(in);
        void* out = std::aligned_alloc(alignof(std::string), sizeof(std::string) * sz)
    ) {
        try {
            auto first {static_cast<std::string*>(out)};
            auto last {first + sz};
            std::uninitialized_move(std::begin(in), std::end(in), first);
            print("after move, in: ", std::begin(in), std::end(in));
            print("after move, out: ", first, last);
            std::destroy(first, last);
        catch (...) {
            std::cout << "Exception!\n";

Possible output:

initially, in: "Home" "Work!"
after move, in: "" ""
after move, out: "Home" "Work!"

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3870 C++20 this algorithm might create objects on a const storage kept disallowed

[edit] See also

copies a range of objects to an uninitialized area of memory
(function template) [edit]
moves a number of objects to an uninitialized area of memory
(function template) [edit]
moves a range of objects to an uninitialized area of memory
(niebloid) [edit]