11448 - Who said crisis/bigint-2007.07.07/sample.cc

   1 /*
   2 * Matt McCutchen's Big Integer Library
   3 *
   4 * Sample program demonstrating the most important features of the Big
   5 * Integer Library
   6 */
   7
   8 // Standard libraries
   9 #include <string>
  10 #include <iostream>
  11
  12 // For the BigInteger class itself.
  13 #include "BigInteger.hh"
  14
  15 // For the 4 routines `easy BI/BU <=> string' and `iostream' integration.
  16 #include "BigIntegerUtils.hh"
  17
  18 int main() {
  19         try {
  20                 BigInteger a; // a is 0
  21                 int b = 535;
  22
  23                 a = b; // From int to BigInteger...
  24                 b = a; // ...and back, no casts required!
  25                 /*
  26                 * If a were too big for an int you'd get a runtime exception.
  27                 * The Big Integer Library throws C-strings (that is,
  28                 * `const char *'s) when something goes wrong.  It's a good idea
  29                 * to catch them; the `try/catch' construct wrapping all this
  30                 * code is an example of how to do this.  Some C++ compilers need
  31                 * a special command-line option to compile code that uses
  32                 * exceptions.
  33                 */
  34
  35                 BigInteger c(a); // Copy a BigInteger.
  36
  37                 // d is -314159265.  The `int' literal is converted to a
  38                 // BigInteger.
  39                 BigInteger d(-314159265);
  40
  41                 // This won't compile because the number is too big to be an
  42                 // integer literal.
  43                 //BigInteger e(3141592653589793238462643383279);
  44
  45                 // Instead you can convert the number from a string.
  46                 std::string s("3141592653589793238462643383279");
  47                 BigInteger f = easyStringToBI(s);
  48
  49                 // You can convert the other way too.
  50                 std::string s2 = easyBItoString(f);
  51
  52                 // f is stringified and send to std::cout.
  53                 std::cout << f << std::endl;
  54
  55                 /*
  56                 * Let's do some math!
  57                 *
  58                 * The Big Integer Library provides lots of overloaded operators
  59                 * and corresponding assignment operators.  So you can do `a + b'
  60                 * with BigIntegers just as with normal integers.  The named
  61                 * methods `add', `divideWithRemainder', etc. are more advanced
  62                 * ``put-here operations''; see `BigUnsigned.hh' for details.
  63                 */
  64                 BigInteger g(314159), h(265);
  65                 // All five ``return-by-value'' arithmetic operators.
  66                 std::cout << (g + h) << '\n' << (g - h) << '\n' << (g * h)
  67                         << '\n' << (g / h) << '\n' << (g % h) << std::endl;
  68
  69                 BigUnsigned i(0xFF0000FF), j(0x0000FFFF);
  70                 // All five ``return-by-value'' bitwise operators.
  71                 std::cout.flags(std::ios::hex | std::ios::showbase);
  72                 std::cout << (i & j) << '\n' << (i | j) << '\n' << (i ^ j) << '\n'
  73                         << (j << 21) << '\n' << (j >> 10) << '\n';
  74                 std::cout.flags(std::ios::dec);
  75
  76                 // Let's do some heavy lifting and calculate powers of 314.
  77                 int maxPower = 10;
  78                 BigUnsigned x(1), big314(314);
  79                 for (int power = 0; power <= maxPower; power++) {
  80                         std::cout << "314^" << power << " = " << x << std::endl;
  81                         x *= big314; // A BigInteger assignment operator
  82                 }
  83
  84                 /*
  85                 * If you want to experiment with the library,
  86                 * you can add your own test code here.
  87                 */
  88                 // std::cout << "Beginning of custom test code:" << std::endl;
  89
  90         } catch(char const* err) {
  91                 std::cout << "The library threw an exception:\n"
  92                         << err << std::endl;
  93         }
  94
  95         return 0;
  96 }
  97
  98 /*
  99 Running the sample program produces this output:
 100
 101 3141592653589793238462643383279
 102 314424
 103 313894
 104 83252135
 105 1185
 106 134
 107 0xFF
 108 0xFF00FFFF
 109 0xFF00FF00
 110 0x1FFFE00000
 111 0x3F
 112 314^0 = 1
 113 314^1 = 314
 114 314^2 = 98596
 115 314^3 = 30959144
 116 314^4 = 9721171216
 117 314^5 = 3052447761824
 118 314^6 = 958468597212736
 119 314^7 = 300959139524799104
 120 314^8 = 94501169810786918656
 121 314^9 = 29673367320587092457984
 122 314^10 = 9317437338664347031806976
 123
 124 */