ceph/src/boost/libs/safe_numerics/example/example14.cpp

   1 //  Copyright (c) 2018 Robert Ramey
   2 //
   3 // Distributed under the Boost Software License, Version 1.0. (See
   4 // accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #include <stdexcept>
   8 #include <iostream>
   9
  10 #include <boost/safe_numerics/safe_integer.hpp>
  11
  12 int main(int, const char *[]){
  13     // problem: cannot recover from arithmetic errors
  14     std::cout << "example 8: ";
  15     std::cout << "cannot detect compile time arithmetic errors" << std::endl;
  16     std::cout << "Not using safe numerics" << std::endl;
  17
  18     try{
  19         const int x = 1;
  20         const int y = 0;
  21         // will emit warning at compile time
  22         // will leave an invalid result at runtime.
  23         std::cout << x / y; // will display "0"!
  24         std::cout << "error NOT detected!" << std::endl;
  25     }
  26     catch(const std::exception &){
  27         std::cout << "error detected!" << std::endl;
  28     }
  29     // solution: replace int with safe<int>
  30     std::cout << "Using safe numerics" << std::endl;
  31     try{
  32         using namespace boost::safe_numerics;
  33         const safe<int> x = 1;
  34         const safe<int> y = 0;
  35         // constexpr const safe<int> z = x / y; // note constexpr here!
  36         std::cout << x / y; // error would be detected at runtime
  37         std::cout << " error NOT detected!" << std::endl;
  38     }
  39     catch(const std::exception & e){
  40         std::cout << "error detected:" << e.what() << std::endl;
  41     }
  42     return 0;
  43 }