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1 | /* |
2 | * Matt McCutchen's Big Integer Library | |
3 | * http://mysite.verizon.net/mccutchen/bigint/ | |
4 | */ | |
5 | ||
6 | /* | |
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7 | * This sample program demonstrates the most important features of the Big Integer Library. |
8 | * To get started quickly, read the code and explanations below. Then try the program out. | |
05780f4b | 9 | * |
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10 | * If you want more detail or more speed or can't find a feature here, look in the |
11 | * appropriate source file. This file shows only the more ``user-friendly'' features; | |
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12 | * the other features are messier but worth learning eventually. |
13 | * | |
14 | * GO FORTH and play with many-digit numbers! (c.f. The TeXbook.) | |
15 | */ | |
16 | ||
b3fe29df | 17 | // Standard libraries |
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18 | #include <string> |
19 | #include <iostream> | |
20 | ||
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21 | // For the BigInteger class itself. |
22 | #include "BigInteger.hh" | |
23 | ||
24 | // For the 4 routines `easy BI/BU <=> string' and `iostream' integration. | |
25 | #include "BigIntegerUtils.hh" | |
26 | ||
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27 | int main() { |
28 | try { | |
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29 | std::cout << "=====\nBig Integer Library Demonstration" << std::endl; |
30 | ||
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31 | BigInteger a; // a is 0 |
32 | int b = 535; | |
33 | ||
b3fe29df | 34 | a = b; // From int to BigInteger... |
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35 | b = a; // ...and back, no casts required! |
36 | /* | |
37 | * If a were too big for an int you'd get a runtime exception. The Big Integer Library | |
38 | * throws C-strings (that is, `const char *'s) when something goes wrong. It's a good | |
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39 | * idea to catch them; the `try/catch' construct wrapping all this code is an example |
40 | * of how to do this. Some C++ compilers need a special command-line option to compile | |
41 | * code that uses exceptions. | |
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42 | */ |
43 | ||
b3fe29df | 44 | BigInteger c(a); // Copy a BigInteger. |
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45 | |
46 | BigInteger d(-314159265); // c is -314159265. The `int' literal is converted to a BigInteger. | |
47 | ||
48 | // Ahem: that's too big to be an `int' literal (or even a `long' literal)! | |
49 | // Disillusion yourself now -- this won't compile. | |
50 | //BigInteger e(3141592653589793238462643383279); | |
51 | ||
52 | std::string s("3141592653589793238462643383279"); | |
53 | BigInteger f = easyStringToBI(s); | |
54 | // Ah. The string is converted to a BigInteger, and strings can be as long as you want. | |
55 | ||
56 | std::string s2 = easyBItoString(f); // You can convert the other way too. | |
57 | ||
58 | std::cout << f << std::endl; // f is stringified and send to std::cout. | |
59 | ||
60 | /* | |
61 | * Let's do some math! | |
62 | * | |
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63 | * The Big Integer Library provides lots of overloaded operators |
64 | * and corresponding assignment operators. So you can do `a + b' | |
65 | * with big integers just as with normal integers. The named | |
66 | * methods `add', `divideWithRemainder', etc. are more advanced | |
67 | * ``put-here operations''; see `BigUnsigned.hh' for details. | |
05780f4b | 68 | */ |
05780f4b | 69 | BigInteger g(314159), h(265); |
a8b42b68 | 70 | // All five ``return-by-value'' operators. |
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71 | std::cout << (g + h) << '\n' << (g - h) << '\n' << (g * h) |
72 | << '\n' << (g / h) << '\n' << (g % h) << std::endl; | |
73 | ||
a8b42b68 | 74 | std::cout << "=====\nTest code" << std::endl; |
e257a1b2 | 75 | |
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76 | /* |
77 | * If you want to experiment with the library, | |
78 | * put your own test code here. | |
79 | */ | |
05780f4b | 80 | |
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81 | /* |
82 | * (End of test code) | |
83 | */ | |
e257a1b2 | 84 | |
05780f4b | 85 | // Let's do some heavy lifting. |
a8b42b68 | 86 | std::cout << "=====\nPowers of 3" << std::endl; |
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87 | std::cout << "How many do you want?" << std::endl; |
88 | int maxPower; | |
89 | std::cin >> maxPower; | |
90 | ||
91 | BigUnsigned x(1), three(3); | |
92 | for (int power = 0; power <= maxPower; power++) { | |
93 | std::cout << "3^" << power << " = " << x << std::endl; | |
94 | x *= three; // A BigInteger assignment operator | |
95 | } | |
96 | ||
a8b42b68 | 97 | std::cout << "There you go. Goodbye.\n=====" << std::endl; |
05780f4b | 98 | |
b3fe29df | 99 | } catch(char const* err) { |
a8b42b68 | 100 | std::cout << "=====\nSorry, the library threw an exception:\n" |
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101 | << err << std::endl; |
102 | } | |
b3fe29df | 103 | |
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104 | return 0; |
105 | } | |
106 | ||
107 | /* | |
108 | * Here is the output of a sample run of this sample program: | |
109 | ||
110 | 3141592653589793238462643383279 | |
111 | 314424 | |
112 | 313894 | |
113 | 83252135 | |
114 | 1185 | |
115 | 134 | |
116 | Powers of 3 | |
117 | How many do you want? | |
118 | 2 | |
119 | 3^0 = 1 | |
120 | 3^1 = 3 | |
121 | 3^2 = 9 | |
122 | There you go. Goodbye. | |
123 | ||
124 | */ |