ParallelAlgorithms.cpp

#include <hpx/hpx_init.hpp>
#include <hpx/hpx.hpp>
#include <hpx/include/algorithm.hpp>

//...

std::vector<int> c(10007);
//fill the vector with random values
std::iota(boost::begin(c), boost::end(c), std::rand());

int const val = 42;
auto op = 
  [val](int v1, int v2) {
    return v1 + v2 + val;
  };
  
//call reduce with a parallel execution policy
int r1 = hpx::parallel::reduce(hpx::parallel::par,
  boost::begin(c), boost::end(c), val, op);
  
//the above execution is equivalent to:
int r2 = std::accumulate(boost::begin(c), boost::end(c), val, op);

//these values are the SAME, but the parallel execution is much faster!
HPX_TEST_EQ(r1, r2);


/////////////////////////////////////////////////////////////////////////////////////
//using futures

std::vector<int> c(10007);
//fill vector with random values
std::iota(boost::begin(c), boost::end(c), std::rand());

int const val = 42;
hpx::future<int> f =
  hpx::parallel::reduce(hpx::parallel::task,
    boost::begin(c), boost::end(c), val)

//wait for future
f.wait();