ceph/src/boost/libs/safe_numerics/example/example10.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 <iostream>
   8 #include <cstdint>
   9
  10 #include <boost/safe_numerics/safe_integer.hpp>
  11
  12 using namespace std;
  13 using namespace boost::safe_numerics;
  14
  15 void f(const unsigned int & x, const int8_t & y){
  16     cout << x * y << endl;
  17 }
  18 void safe_f(
  19     const safe<unsigned int> & x,
  20     const safe<int8_t> & y
  21 ){
  22     cout << x * y << endl;
  23 }
  24
  25 int main(){
  26     cout << "example 4: ";
  27     cout << "mixing types produces surprising results" << endl;
  28     try {
  29         std::cout << "Not using safe numerics" << std::endl;
  30         // problem: mixing types produces surprising results.
  31         f(100, 100);  // works as expected
  32         f(100, -100); // wrong result - unnoticed
  33         cout << "error NOT detected!" << endl;;
  34     }
  35     catch(const std::exception & e){
  36         // never arrive here
  37         cout << "error detected:" << e.what() << endl;;
  38     }
  39     try {
  40         // solution: use safe types
  41         std::cout << "Using safe numerics" << std::endl;
  42         safe_f(100, 100);  // works as expected
  43         safe_f(100, -100); // throw error
  44         cout << "error NOT detected!" << endl;;
  45     }
  46     catch(const std::exception & e){
  47         cout << "error detected:" << e.what() << endl;;
  48     }
  49     return 0;
  50 }
  51