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 <iostream>
8
9#include <boost/safe_numerics/safe_integer.hpp>
10
11int main(){
12 std::cout << "example 4: ";
13 std::cout << "implicit conversions change data values" << std::endl;
14 std::cout << "Not using safe numerics" << std::endl;
15
16 // problem: implicit conversions change data values
17 try{
18 signed int a{-1};
19 unsigned int b{1};
20 std::cout << "a is " << a << " b is " << b << '\n';
21 if(a < b){
22 std::cout << "a is less than b\n";
23 }
24 else{
25 std::cout << "b is less than a\n";
26 }
27 std::cout << "error NOT detected!" << std::endl;
28 }
29 catch(const std::exception &){
30 // never arrive here - just produce the wrong answer!
31 std::cout << "error detected!" << std::endl;
32 return 1;
33 }
34
35 // solution: replace int with safe<int> and unsigned int with safe<unsigned int>
36 std::cout << "Using safe numerics" << std::endl;
37 try{
38 using namespace boost::safe_numerics;
39 safe<signed int> a{-1};
40 safe<unsigned int> b{1};
41 std::cout << "a is " << a << " b is " << b << '\n';
42 if(a < b){
43 std::cout << "a is less than b\n";
44 }
45 else{
46 std::cout << "b is less than a\n";
47 }
48 std::cout << "error NOT detected!" << std::endl;
49 return 1;
50 }
51 catch(const std::exception & e){
52 // never arrive here - just produce the correct answer!
53 std::cout << e.what() << std::endl;
54 std::cout << "error detected!" << std::endl;
55 }
56 return 0;
57}
58

source code of boost/libs/safe_numerics/example/example4.cpp