ceph/src/boost/libs/thread/tutorial/factorial.cpp

   1 // Copyright (C) 2001-2003
   2 // William E. Kempf
   3 //
   4 //  Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #include <boost/thread/thread.hpp>
   8 #include <iostream>
   9
  10 class factorial
  11 {
  12 public:
  13     factorial(int x, int& res) : x(x), res(res) { }
  14     void operator()() { res = calculate(x); }
  15     int result() const { return res; }
  16
  17 private:
  18     int calculate(int x) { return x <= 1 ? 1 : x * calculate(x-1); }
  19
  20 private:
  21     int x;
  22     int& res;
  23 };
  24
  25 int main()
  26 {
  27     int result;
  28     factorial f(10, result);
  29     boost::thread thrd(f);
  30     thrd.join();
  31     std::cout << "10! = " << result << std::endl;
  32 }