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