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// Copyright (c) 2018 Robert Ramey
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#include <iostream>
#include <boost/safe_numerics/safe_integer.hpp>
int main(int, const char *[]){
std::cout << "example 8:";
std::cout << "undetected erroneous expression evaluation" << std::endl;
std::cout << "Not using safe numerics" << std::endl;
try{
unsigned int x = 127;
unsigned int y = 2;
unsigned int z;
// this produces an invalid result !
z = y - x;
std::cout << "error NOT detected!" << std::endl;
std::cout << z << " != " << y << " - " << x << std::endl;
}
catch(const std::exception &){
std::cout << "error detected!" << std::endl;
}
// solution: replace int with safe<int>
std::cout << "Using safe numerics" << std::endl;
try{
using namespace boost::safe_numerics;
safe<unsigned int> x = 127;
safe<unsigned int> y = 2;
safe<unsigned int> z;
// rather than producing an invalid result an exception is thrown
z = y - x;
std::cout << "error NOT detected!" << std::endl;
std::cout << z << " != " << y << " - " << x << std::endl;
}
catch(const std::exception & e){
// which we can catch here
std::cout << "error detected:" << e.what() << std::endl;
}
return 0;
}
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