mirror of
https://github.com/boostorg/safe_numerics.git
synced 2026-02-03 09:22:19 +00:00
434ce2cd05
fixed up CMake files so that they run from the command line adjusted CMake files so that they exclude tests which can't be run
71 lines
2.4 KiB
C++
71 lines
2.4 KiB
C++
#include <cassert>
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#include <exception>
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#include <iostream>
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#include <cstdint>
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#include "../include/safe_integer.hpp"
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int main(int argc, const char * argv[]){
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std::cout << "example 1:";
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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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int x = INT_MAX;
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int y = 2;
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int z;
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// this produces an invalid result !
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z = x + y;
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// but assert fails to detect it since C++ implicitly
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// converts variables to int before evaluating he expression!
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std::cout << "x == " << x << '\n';
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std::cout << "y == " << y << '\n';
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std::cout << "z == " << z << '\n';
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std::cout << std::boolalpha;
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std::cout << "does z == x + y? " << (z == x + y) << std::endl;
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assert(z == x + y);
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std::cout << z << " != " << x + y << std::endl;
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std::cout << "error NOT detected!" << std::endl;
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}
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catch(std::exception){
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std::cout << "error detected!" << std::endl;
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}
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// problem: arithmetic operations can yield incorrect results.
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try{
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std::int8_t x = 127;
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std::int8_t y = 2;
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std::int8_t z;
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// this produces an invalid result !
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z = x + y;
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// but assert fails to detect it since C++ implicitly
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// converts variables to int before evaluating he expression!
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std::cout << "x == " << static_cast<int>(x) << '\n';
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std::cout << "y == " << static_cast<int>(y) << '\n';
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std::cout << "z == " << static_cast<int>(z) << '\n';
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std::cout << std::boolalpha;
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std::cout << "does z == x + y? " << (z == x + y) << std::endl;
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// assert(z == x + y);
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std::cout << static_cast<int>(z) << " != " << x + y << std::endl;
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std::cout << "error NOT detected!" << std::endl;
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}
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catch(std::exception){
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std::cout << "error detected!" << std::endl;
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}
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// solution: replace std::int8_t with safe<std::int8_t>
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std::cout << "Using safe numerics" << std::endl;
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try{
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using namespace boost::numeric;
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safe<std::int8_t> x = 127;
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safe<std::int8_t> y = 2;
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safe<std::int8_t> z;
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// rather than producing and invalid result an exception is thrown
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z = x + y;
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}
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catch(std::exception & e){
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// which can catch here
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std::cout << e.what() << std::endl;
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}
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return 0;
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}
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