2 * Matt McCutchen's Big Integer Library
3 * http://mysite.verizon.net/mccutchen/bigint/
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.
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;
12 * the other features are messier but worth learning eventually.
14 * GO FORTH and play with many-digit numbers! (c.f. The TeXbook.)
21 // For the BigInteger class itself.
22 #include "BigInteger.hh"
24 // For the 4 routines `easy BI/BU <=> string' and `iostream' integration.
25 #include "BigIntegerUtils.hh"
29 std::cout << "=====\nBig Integer Library Demonstration" << std::endl;
31 BigInteger a; // a is 0
34 a = b; // From int to BigInteger...
35 b = a; // ...and back, no casts required!
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
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.
44 BigInteger c(a); // Copy a BigInteger.
46 BigInteger d(-314159265); // c is -314159265. The `int' literal is converted to a BigInteger.
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);
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.
56 std::string s2 = easyBItoString(f); // You can convert the other way too.
58 std::cout << f << std::endl; // f is stringified and send to std::cout.
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.
69 BigInteger g(314159), h(265);
70 // All five ``return-by-value'' operators.
71 std::cout << (g + h) << '\n' << (g - h) << '\n' << (g * h)
72 << '\n' << (g / h) << '\n' << (g % h) << std::endl;
74 std::cout << "=====\nTest code" << std::endl;
77 * If you want to experiment with the library,
78 * put your own test code here.
85 // Let's do some heavy lifting.
86 std::cout << "=====\nPowers of 3" << std::endl;
87 std::cout << "How many do you want?" << std::endl;
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
97 std::cout << "There you go. Goodbye.\n=====" << std::endl;
99 } catch(char const* err) {
100 std::cout << "=====\nSorry, the library threw an exception:\n"
108 * Here is the output of a sample run of this sample program:
110 3141592653589793238462643383279
117 How many do you want?
122 There you go. Goodbye.