Old snapshot `BigIntegerLibrary-2004.12.24.2'; see the ChangeLog file.

[bigint/bigint.git] / BigIntegerUtils.cc

diff --git a/BigIntegerUtils.cc b/BigIntegerUtils.cc
new file mode 100644 (file)
index 0000000..f7f1cbc
--- /dev/null
+++ b/BigIntegerUtils.cc
@@ -0,0 +1,61 @@
+/*
+* Matt McCutchen's Big Integer Library
+* http://mysite.verizon.net/mccutchen/bigint/
+*/
+
+#include "BigIntegerUtils.hh"
+#include "BigUnsignedInABase.hh"
+
+/*
+* This file includes:
+* (1) `std::string <=> BigUnsigned/BigInteger' conversion routines easier than `BigUnsignedInABase'
+* (2) << and >> operators for BigUnsigned/BigInteger, std::istream/std::ostream
+*/
+
+std::string easyBUtoString(const BigUnsigned &x) {
+       return std::string(BigUnsignedInABase(x, 10));
+}
+
+std::string easyBItoString(const BigInteger &x) {
+       return (x.getSign() == BigInteger::negative) ?
+               (std::string("-") + easyBUtoString(x)) : (easyBUtoString(x));
+}
+
+BigUnsigned easyStringToBU(const std::string &s) {
+       return BigUnsigned(BigUnsignedInABase(s, 10));
+}
+
+BigInteger easyStringToBI(const std::string &s) {
+       return (s[0] == '-') ?
+               BigInteger(easyStringToBU(s.substr(1, s.length() - 1)), BigInteger::negative) :
+               BigInteger(easyStringToBU(s));
+}
+
+// Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'.
+std::ostream &operator <<(std::ostream &os, const BigUnsigned &x) {
+       BigUnsignedInABase::Base base;
+       long osFlags = os.flags();
+       if (osFlags & os.dec)
+               base = 10;
+       else if (osFlags & os.hex) {
+               base = 16;
+               if (osFlags & os.showbase)
+                       os << "0x";
+       } else if (osFlags & os.oct) {
+               base = 8;
+               if (osFlags & os.showbase)
+                       os << '0';
+       } else
+               throw "std::ostream << BigUnsigned: Could not determine the desired base from output-stream flags";
+       std::string s = std::string(BigUnsignedInABase(x, base));
+       os << s;
+       return os;
+}
+// Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'.
+// My somewhat arbitrary policy: a negative sign comes before a base indicator (like -0xFF).
+std::ostream &operator <<(std::ostream &os, const BigInteger &x) {
+       if (x.getSign() == BigInteger::negative)
+               os << '-';
+       os << (const BigUnsigned &)(x);
+       return os;
+}