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// Copyright (C) 2001-2003
// William E. Kempf
//
// Permission to use, copy, modify, distribute and sell this software
// and its documentation for any purpose is hereby granted without fee,
// provided that the above copyright notice appear in all copies and
// that both that copyright notice and this permission notice appear
// in supporting documentation. William E. Kempf makes no representations
// about the suitability of this software for any purpose.
// It is provided "as is" without express or implied warranty.
#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;
}
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