1 // Copyright (c) 2018 Robert Ramey 2 // 3 // Distributed under the Boost Software License, Version 1.0. (See 4 // accompanying file LICENSE_1_0.txt or copy at 5 // http://www.boost.org/LICENSE_1_0.txt) 6 7 #include <stdexcept> 8 #include <iostream> 9 #include <array> 10 11 #include <boost/safe_numerics/safe_integer_range.hpp> 12 detected_msg(bool detected)13void detected_msg(bool detected){ 14 std::cout << (detected ? "error detected!" : "error NOT detected! ") << std::endl; 15 } 16 main(int,const char * [])17int main(int, const char *[]){ 18 // problem: array index values can exceed array bounds 19 std::cout << "example 5: "; 20 std::cout << "array index values can exceed array bounds" << std::endl; 21 std::cout << "Not using safe numerics" << std::endl; 22 std::array<int, 37> i_array; 23 24 // unsigned int i_index = 43; 25 // the following corrupts memory. 26 // This may or may not be detected at run time. 27 // i_array[i_index] = 84; // comment this out so it can be tested! 28 std::cout << "error NOT detected!" << std::endl; 29 30 // solution: replace unsigned array index with safe_unsigned_range 31 std::cout << "Using safe numerics" << std::endl; 32 try{ 33 using namespace boost::safe_numerics; 34 using i_index_t = safe_unsigned_range<0, i_array.size() - 1>; 35 i_index_t i_index; 36 i_index = 36; // this works fine 37 i_array[i_index] = 84; 38 i_index = 43; // throw exception here! 39 std::cout << "error NOT detected!" << std::endl; // so we never arrive here 40 } 41 catch(const std::exception & e){ 42 std::cout << "error detected:" << e.what() << std::endl; 43 } 44 return 0; 45 } 46