Template Function thrust::for_each_n(InputIterator, Size, UnaryFunction)¶

Function Documentation¶

template<typename InputIterator, typename Size, typename UnaryFunction> InputIterator thrust::for_each_n(InputIterator first, Size n, UnaryFunction f)

for_each_n applies the function object f to each element in the range [first, first + n); f's return value, if any, is ignored. Unlike the C++ Standard Template Library function std::for_each, this version offers no guarantee on order of execution.

The following code snippet demonstrates how to use

for_each_n to print the elements of a device_vector.

Return

first + n

Parameters

first: The beginning of the sequence.
n: The size of the input sequence.
f: The function object to apply to the range [first, first + n).

Template Parameters

InputIterator: is a model of Input Iterator, and InputIterator's value_type is convertible to UnaryFunction's argument_type.
Size: is an integral type.
UnaryFunction: is a model of Unary Function, and UnaryFunction does not apply any non-constant operation through its argument.

#include <thrust/for_each.h>
#include <thrust/device_vector.h>
#include <stdio.h>

struct printf_functor
{
  __host__ __device__
  void operator()(int x)
  {
    // note that using printf in a __device__ function requires
    // code compiled for a GPU with compute capability 2.0 or
    // higher (nvcc --arch=sm_20)
    printf("%d\n", x);
  }
};
...
thrust::device_vector<int> d_vec(3);
d_vec[0] = 0; d_vec[1] = 1; d_vec[2] = 2;

thrust::for_each_n(d_vec.begin(), d_vec.size(), printf_functor());

// 0 1 2 is printed to standard output in some unspecified order

See: for_each
See: http://www.sgi.com/tech/stl/for_each.html