| 1 | // Sample program demonstrating the use of the Big Integer Library. |
| 2 | |
| 3 | // Standard libraries |
| 4 | #include <string> |
| 5 | #include <iostream> |
| 6 | |
| 7 | // `BigIntegerLibrary.hh' includes all of the library headers. |
| 8 | #include "BigIntegerLibrary.hh" |
| 9 | |
| 10 | int main() { |
| 11 | /* The library throws `const char *' error messages when things go |
| 12 | * wrong. It's a good idea to catch them using a `try' block like this |
| 13 | * one. Your C++ compiler might need a command-line option to compile |
| 14 | * code that uses exceptions. */ |
| 15 | try { |
| 16 | BigInteger a; // a is 0 |
| 17 | int b = 535; |
| 18 | |
| 19 | /* Any primitive integer can be converted implicitly to a |
| 20 | * BigInteger. */ |
| 21 | a = b; |
| 22 | |
| 23 | /* The reverse conversion requires a method call (implicit |
| 24 | * conversions were previously supported but caused trouble). |
| 25 | * If a were too big for an int, the library would throw an |
| 26 | * exception. */ |
| 27 | b = a.toInt(); |
| 28 | |
| 29 | BigInteger c(a); // Copy a BigInteger. |
| 30 | |
| 31 | // The int literal is converted to a BigInteger. |
| 32 | BigInteger d(-314159265); |
| 33 | |
| 34 | /* This won't compile (at least on 32-bit machines) because the |
| 35 | * number is too big to be a primitive integer literal, and |
| 36 | * there's no such thing as a BigInteger literal. */ |
| 37 | //BigInteger e(3141592653589793238462643383279); |
| 38 | |
| 39 | // Instead you can convert the number from a string. |
| 40 | std::string s("3141592653589793238462643383279"); |
| 41 | BigInteger f = stringToBigInteger(s); |
| 42 | |
| 43 | // You can convert the other way too. |
| 44 | std::string s2 = bigIntegerToString(f); |
| 45 | |
| 46 | // f is implicitly stringified and sent to std::cout. |
| 47 | std::cout << f << std::endl; |
| 48 | |
| 49 | /* Let's do some math! The library overloads most of the |
| 50 | * mathematical operators (including assignment operators) to |
| 51 | * work on BigIntegers. There are also ``copy-less'' |
| 52 | * operations; see `BigUnsigned.hh' for details. */ |
| 53 | |
| 54 | // Arithmetic operators |
| 55 | BigInteger g(314159), h(265); |
| 56 | std::cout << (g + h) << '\n' |
| 57 | << (g - h) << '\n' |
| 58 | << (g * h) << '\n' |
| 59 | << (g / h) << '\n' |
| 60 | << (g % h) << std::endl; |
| 61 | |
| 62 | // Bitwise operators |
| 63 | BigUnsigned i(0xFF0000FF), j(0x0000FFFF); |
| 64 | // The library's << operator recognizes base flags. |
| 65 | std::cout.flags(std::ios::hex | std::ios::showbase); |
| 66 | std::cout << (i & j) << '\n' |
| 67 | << (i | j) << '\n' |
| 68 | << (i ^ j) << '\n' |
| 69 | // Shift distances are ordinary unsigned ints. |
| 70 | << (j << 21) << '\n' |
| 71 | << (j >> 10) << '\n'; |
| 72 | std::cout.flags(std::ios::dec); |
| 73 | |
| 74 | // Let's do some heavy lifting and calculate powers of 314. |
| 75 | int maxPower = 10; |
| 76 | BigUnsigned x(1), big314(314); |
| 77 | for (int power = 0; power <= maxPower; power++) { |
| 78 | std::cout << "314^" << power << " = " << x << std::endl; |
| 79 | x *= big314; // A BigInteger assignment operator |
| 80 | } |
| 81 | |
| 82 | // Some big-integer algorithms (albeit on small integers). |
| 83 | std::cout << gcd(BigUnsigned(60), 72) << '\n' |
| 84 | << modinv(BigUnsigned(7), 11) << '\n' |
| 85 | << modexp(BigUnsigned(314), 159, 2653) << std::endl; |
| 86 | |
| 87 | // Add your own code here to experiment with the library. |
| 88 | } catch(char const* err) { |
| 89 | std::cout << "The library threw an exception:\n" |
| 90 | << err << std::endl; |
| 91 | } |
| 92 | |
| 93 | return 0; |
| 94 | } |
| 95 | |
| 96 | /* |
| 97 | The original sample program produces this output: |
| 98 | |
| 99 | 3141592653589793238462643383279 |
| 100 | 314424 |
| 101 | 313894 |
| 102 | 83252135 |
| 103 | 1185 |
| 104 | 134 |
| 105 | 0xFF |
| 106 | 0xFF00FFFF |
| 107 | 0xFF00FF00 |
| 108 | 0x1FFFE00000 |
| 109 | 0x3F |
| 110 | 314^0 = 1 |
| 111 | 314^1 = 314 |
| 112 | 314^2 = 98596 |
| 113 | 314^3 = 30959144 |
| 114 | 314^4 = 9721171216 |
| 115 | 314^5 = 3052447761824 |
| 116 | 314^6 = 958468597212736 |
| 117 | 314^7 = 300959139524799104 |
| 118 | 314^8 = 94501169810786918656 |
| 119 | 314^9 = 29673367320587092457984 |
| 120 | 314^10 = 9317437338664347031806976 |
| 121 | 12 |
| 122 | 8 |
| 123 | 1931 |
| 124 | |
| 125 | */ |