2 * Matt McCutchen's Big Integer Library
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.
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;
11 * the other features are messier but worth learning eventually.
13 * GO FORTH and play with many-digit numbers! (c.f. The TeXbook.)
20 // For the BigInteger class itself.
21 #include "BigInteger.hh"
23 // For the 4 routines `easy BI/BU <=> string' and `iostream' integration.
24 #include "BigIntegerUtils.hh"
28 std::cout << "=====\nBig Integer Library Demonstration" << std::endl;
30 BigInteger a; // a is 0
33 a = b; // From int to BigInteger...
34 b = a; // ...and back, no casts required!
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
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.
43 BigInteger c(a); // Copy a BigInteger.
45 BigInteger d(-314159265); // c is -314159265. The `int' literal is converted to a BigInteger.
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);
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.
55 std::string s2 = easyBItoString(f); // You can convert the other way too.
57 std::cout << f << std::endl; // f is stringified and send to std::cout.
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.
68 BigInteger g(314159), h(265);
69 // All five ``return-by-value'' operators.
70 std::cout << (g + h) << '\n' << (g - h) << '\n' << (g * h)
71 << '\n' << (g / h) << '\n' << (g % h) << std::endl;
73 std::cout << "=====\nTest code" << std::endl;
76 * If you want to experiment with the library,
77 * put your own test code here.
84 // Let's do some heavy lifting.
85 std::cout << "=====\nPowers of 3" << std::endl;
86 std::cout << "How many do you want?" << std::endl;
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
96 std::cout << "There you go. Goodbye.\n=====" << std::endl;
98 } catch(char const* err) {
99 std::cout << "=====\nSorry, the library threw an exception:\n"
107 * Here is the output of a sample run of this sample program:
109 3141592653589793238462643383279
116 How many do you want?
121 There you go. Goodbye.