UVa/11448 - Who said crisis/bigint-2007.07.07/BigIntegerUtils.cc

   1 /*
   2 * Matt McCutchen's Big Integer Library
   3 */
   4
   5 #include "BigIntegerUtils.hh"
   6 #include "BigUnsignedInABase.hh"
   7
   8 /*
   9 * This file includes:
  10 * (1) `std::string <=> BigUnsigned/BigInteger' conversion routines easier than `BigUnsignedInABase'
  11 * (2) << and >> operators for BigUnsigned/BigInteger, std::istream/std::ostream
  12 */
  13
  14 std::string easyBUtoString(const BigUnsigned &x) {
  15         return std::string(BigUnsignedInABase(x, 10));
  16 }
  17
  18 std::string easyBItoString(const BigInteger &x) {
  19         return (x.getSign() == BigInteger::negative) ?
  20                 (std::string("-") + easyBUtoString(x)) : (easyBUtoString(x));
  21 }
  22
  23 BigUnsigned easyStringToBU(const std::string &s) {
  24         return BigUnsigned(BigUnsignedInABase(s, 10));
  25 }
  26
  27 BigInteger easyStringToBI(const std::string &s) {
  28         return (s[0] == '-') ?
  29                 BigInteger(easyStringToBU(s.substr(1, s.length() - 1)), BigInteger::negative) :
  30                 BigInteger(easyStringToBU(s));
  31 }
  32
  33 // Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'.
  34 std::ostream &operator <<(std::ostream &os, const BigUnsigned &x) {
  35         BigUnsignedInABase::Base base;
  36         long osFlags = os.flags();
  37         if (osFlags & os.dec)
  38                 base = 10;
  39         else if (osFlags & os.hex) {
  40                 base = 16;
  41                 if (osFlags & os.showbase)
  42                         os << "0x";
  43         } else if (osFlags & os.oct) {
  44                 base = 8;
  45                 if (osFlags & os.showbase)
  46                         os << '0';
  47         } else
  48                 throw "std::ostream << BigUnsigned: Could not determine the desired base from output-stream flags";
  49         std::string s = std::string(BigUnsignedInABase(x, base));
  50         os << s;
  51         return os;
  52 }
  53 // Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'.
  54 // My somewhat arbitrary policy: a negative sign comes before a base indicator (like -0xFF).
  55 std::ostream &operator <<(std::ostream &os, const BigInteger &x) {
  56         if (x.getSign() == BigInteger::negative)
  57                 os << '-';
  58         os << (const BigUnsigned &)(x);
  59         return os;
  60 }