1 //////////////////////////////////////////////////////////////////
2 // example94.cpp
3 //
4 // Copyright (c) 2015 Robert Ramey
5 //
6 // Distributed under the Boost Software License, Version 1.0. (See
7 // accompanying file LICENSE_1_0.txt or copy at
8 // http://www.boost.org/LICENSE_1_0.txt)
9
10 // illustrate usage of safe<int> as drop-in replacement for int in
11 // a more complex library. Use an example from the boost.rational
12 // library with modifications to use safe<int> rather than int
13
14 // rational number example program ----------------------------------------//
15
16 // (C) Copyright Paul Moore 1999. Permission to copy, use, modify, sell
17 // and distribute this software is granted provided this copyright notice
18 // appears in all copies. This software is provided "as is" without express or
19 // implied warranty, and with no claim as to its suitability for any purpose.
20
21 // boostinspect:nolicense (don't complain about the lack of a Boost license)
22 // (Paul Moore hasn't been in contact for years, so there's no way to change the
23 // license.)
24
25 // Revision History
26 // 14 Dec 99 Initial version
27
28 #include <iostream>
29 #include <cassert>
30 #include <cstdlib>
31 #include <boost/config.hpp>
32 #include <limits>
33 #include <exception>
34 #include <boost/rational.hpp>
35
36 #include <boost/safe_numerics/safe_integer.hpp>
37
38 using std::cout;
39 using std::endl;
40 using boost::rational;
41 using namespace boost::safe_numerics;
42
43 using int_type = safe<int>;
44
main()45 int main ()
46 {
47 rational<int_type> half(1,2);
48 rational<int_type> one(1);
49 rational<int_type> two(2);
50
51 // Some basic checks
52 assert(half.numerator() == 1);
53 assert(half.denominator() == 2);
54 // assert(boost::rational_cast<double>(half) == 0.5);
55
56 static_assert(
57 ! boost::safe_numerics::is_safe<rational<int_type>>::value,
58 "rational<int_type> is safe"
59 );
60
61 // Arithmetic
62 assert(half + half == one);
63 assert(one - half == half);
64 assert(two * half == one);
65 assert(one / half == two);
66
67 // With conversions to integer
68 assert(half+half == 1);
69 assert(2 * half == one);
70 assert(2 * half == 1);
71 assert(one / half == 2);
72 assert(1 / half == 2);
73
74 // Sign handling
75 rational<int_type> minus_half(-1,2);
76 assert(-half == minus_half);
77 assert(abs(minus_half) == half);
78
79 // Do we avoid overflow?
80 int maxint = (std::numeric_limits<int>::max)();
81 rational<int_type> big(maxint, 2);
82 assert(2 * big == maxint);
83
84 // Print some of the above results
85 cout << half << "+" << half << "=" << one << endl;
86 cout << one << "-" << half << "=" << half << endl;
87 cout << two << "*" << half << "=" << one << endl;
88 cout << one << "/" << half << "=" << two << endl;
89 cout << "abs(" << minus_half << ")=" << half << endl;
90 cout << "2 * " << big << "=" << maxint
91 << " (rational: " << rational<int>(maxint) << ")" << endl;
92
93 // Some extras
94 // rational<int_type> pi(22,7);
95 // cout << "pi = " << boost::rational_cast<double>(pi) << " (nearly)" << endl;
96
97 // Exception handling
98 try {
99 rational<int_type> r; // Forgot to initialise - set to 0
100 r = 1/r; // Boom!
101 }
102 catch (const boost::bad_rational &e) {
103 cout << "Bad rational, as expected: " << e.what() << endl;
104 }
105 catch (...) {
106 cout << "Wrong exception raised!" << endl;
107 }
108 return 0;
109 }
110