| 1 | // Copyright (c) 2018 Robert Ramey |
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| 2 | // |
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| 3 | // Distributed under the Boost Software License, Version 1.0. (See |
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| 4 | // accompanying file LICENSE_1_0.txt or copy at |
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| 5 | // http://www.boost.org/LICENSE_1_0.txt) |
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| 6 | |
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| 7 | #include <iostream> |
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| 8 | |
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| 9 | #include <boost/safe_numerics/safe_integer.hpp> |
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| 10 | |
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| 11 | int main(int, const char * []){ |
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| 12 | std::cout << "example 1:" ; |
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| 13 | std::cout << "undetected erroneous expression evaluation" << std::endl; |
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| 14 | std::cout << "Not using safe numerics" << std::endl; |
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| 15 | // problem: arithmetic operations can yield incorrect results. |
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| 16 | try{ |
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| 17 | std::int8_t x = 127; |
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| 18 | std::int8_t y = 2; |
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| 19 | std::int8_t z; |
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| 20 | // this produces an invalid result ! |
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| 21 | z = x + y; |
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| 22 | std::cout << z << " != " << x + y << std::endl; |
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| 23 | std::cout << "error NOT detected!" << std::endl; |
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| 24 | } |
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| 25 | catch(const std::exception &){ |
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| 26 | std::cout << "error detected!" << std::endl; |
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| 27 | } |
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| 28 | // solution: replace std::int8_t with safe<std::int8_t> |
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| 29 | std::cout << "Using safe numerics" << std::endl; |
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| 30 | try{ |
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| 31 | using namespace boost::safe_numerics; |
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| 32 | safe<std::int8_t> x = 127; |
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| 33 | safe<std::int8_t> y = 2; |
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| 34 | // rather than producing and invalid result an exception is thrown |
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| 35 | x + y; |
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| 36 | } |
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| 37 | catch(const std::exception & e){ |
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| 38 | // which can catch here |
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| 39 | std::cout << e.what() << std::endl; |
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| 40 | } |
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| 41 | return 0; |
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| 42 | } |
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| 43 | |
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