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