ceph/src/boost/libs/safe_numerics/example/example15.cpp

   1 #include <iostream>
   2 #include <limits>
   3
   4 #include <boost/rational.hpp>
   5 #include <boost/safe_numerics/safe_integer.hpp>
   6
   7 int main(int, const char *[]){
   8     // simple demo of rational library
   9     const boost::rational<int> r {1, 2};
  10     std::cout << "r = " << r << std::endl;
  11     const boost::rational<int> q {-2, 4};
  12     std::cout << "q = " << q << std::endl;
  13     // display the product
  14     std::cout << "r * q = " << r * q << std::endl;
  15
  16     // problem: rational doesn't handle integer overflow well
  17     const boost::rational<int> c {1, INT_MAX};
  18     std::cout << "c = " << c << std::endl;
  19     const boost::rational<int> d {1, 2};
  20     std::cout << "d = " << d << std::endl;
  21     // display the product - wrong answer
  22     std::cout << "c * d = " << c * d << std::endl;
  23
  24     // solution: use safe integer in rational definition
  25     using safe_rational = boost::rational<
  26         boost::safe_numerics::safe<int>
  27     >;
  28
  29     // use rationals created with safe_t
  30     const safe_rational sc {1, INT_MAX};
  31     std::cout << "c = " << sc << std::endl;
  32     const safe_rational sd {1, 2};
  33     std::cout << "d = " << sd << std::endl;
  34     std::cout << "c * d = ";
  35     try {
  36         // multiply them. This will overflow
  37         std::cout << sc * sd << std::endl;
  38     }
  39     catch (std::exception const& e) {
  40         // catch exception due to multiplication overflow
  41         std::cout << e.what() << std::endl;
  42     }
  43
  44     return 0;
  45 }