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// William E. Kempf

// Distributed under the Boost Software License, Version 1.0. (See accompanying

// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#include <boost/thread/thread.hpp>

#include <iostream>

const int NUM_CALCS=5;

class factorial

{

public:

factorial(int x, int& res) : x(x), res(res) { }

void operator()() { res = calculate(x); }

int result() const { return res; }

private:

int calculate(int x) { return x <= 1 ? 1 : x * calculate(x-1); }

private:

int x;

int& res;

};

int main()

{

int results[NUM_CALCS];

boost::thread_group thrds;

for (int i=0; i < NUM_CALCS; ++i)

thrds.create_thread(factorial(i*10, results[i]));

thrds.join_all();

for (int j=0; j < NUM_CALCS; ++j)

std::cout << j*10 << "! = " << results[j] << std::endl;

}