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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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