ceph/src/boost/libs/safe_numerics/example/example10.cpp

   1 #include <iostream>
   2 #include <cstdint>
   3
   4 #include <boost/safe_numerics/safe_integer.hpp>
   5
   6 using namespace std;
   7 using namespace boost::safe_numerics;
   8
   9 void f(const unsigned int & x, const int8_t & y){
  10     cout << x * y << endl;
  11 }
  12 void safe_f(
  13     const safe<unsigned int> & x,
  14     const safe<int8_t> & y
  15 ){
  16     cout << x * y << endl;
  17 }
  18
  19 int main(){
  20     cout << "example 4: ";
  21     cout << "mixing types produces surprising results" << endl;
  22     try {
  23         std::cout << "Not using safe numerics" << std::endl;
  24         // problem: mixing types produces surprising results.
  25         f(100, 100);  // works as expected
  26         f(100, -100); // wrong result - unnoticed
  27         cout << "error NOT detected!" << endl;;
  28     }
  29     catch(const std::exception & e){
  30         // never arrive here
  31         cout << "error detected:" << e.what() << endl;;
  32     }
  33     try {
  34         // solution: use safe types
  35         std::cout << "Using safe numerics" << std::endl;
  36         safe_f(100, 100);  // works as expected
  37         safe_f(100, -100); // throw error
  38         cout << "error NOT detected!" << endl;;
  39     }
  40     catch(const std::exception & e){
  41         cout << "error detected:" << e.what() << endl;;
  42     }
  43     return 0;
  44 }
  45