thrust::uninitialized_copy_n

Defined in thrust/uninitialized_copy.h

template<typename DerivedPolicy, typename InputIterator, typename Size, typename ForwardIterator> ForwardIterator thrust::uninitialized_copy_n(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, InputIterator first, Size n, ForwardIterator result)

In thrust, the function thrust::device_new allocates memory for an object and then creates an object at that location by calling a constructor. Occasionally, however, it is useful to separate those two operations. If each iterator in the range [result, result + n) points to uninitialized memory, then uninitialized_copy_n creates a copy of [first, first + n) in that range. That is, for each iterator i in the input, uninitialized_copy_n creates a copy of *i in the location pointed to by the corresponding iterator in the output range by InputIterator's value_type's copy constructor with *i as its argument.

The algorithm’s execution is parallelized as determined by exec.

The following code snippet demonstrates how to use uninitialized_copy to initialize a range of uninitialized memory using the thrust::device execution policy for parallelization:

#include <thrust/uninitialized_copy.h>
#include <thrust/device_malloc.h>
#include <thrust/device_vector.h>
#include <thrust/execution_policy.h>

struct Int
{
  __host__ __device__
  Int(int x) : val(x) {}
  int val;
};
...
const int N = 137;

Int val(46);
thrust::device_vector<Int> input(N, val);
thrust::device_ptr<Int> array = thrust::device_malloc<Int>(N);
thrust::uninitialized_copy_n(thrust::device, input.begin(), N, array);

// Int x = array[i];
// x.val == 46 for all 0 <= i < N

See also

uninitialized_copy

See also

copy

See also

uninitialized_fill

See also

device_new

See also

device_malloc

Parameters

exec – The execution policy to use for parallelization.
first – The first element of the input range to copy from.
n – The number of elements to copy.
result – The first element of the output range to copy to.

Template Parameters

DerivedPolicy – The name of the derived execution policy.
InputIterator – is a model of Input Iterator.
Size – is an integral type.
ForwardIterator – is a model of Forward Iterator, ForwardIterator is mutable, and ForwardIterator's value_type has a constructor that takes a single argument whose type is InputIterator's value_type.

Returns

An iterator pointing to the last element of the output range.

Pre

first may equal result, but the range [first, first + n) and the range [result, result + n) shall not overlap otherwise.