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125 lines
3.3 KiB
C++
125 lines
3.3 KiB
C++
// Sample program demonstrating the use of the Big Integer Library.
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// Standard libraries
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#include <string>
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#include <iostream>
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// `BigIntegerLibrary.hh' includes all of the library headers.
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#include "BigIntegerLibrary.hh"
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int main() {
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/* The library throws `const char *' error messages when things go
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* wrong. It's a good idea to catch them using a `try' block like this
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* one. Your C++ compiler might need a command-line option to compile
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* code that uses exceptions. */
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try {
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BigInteger a; // a is 0
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int b = 535;
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/* Any primitive integer can be converted implicitly to a
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* BigInteger. */
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a = b;
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/* The reverse conversion requires a method call (implicit
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* conversions were previously supported but caused trouble).
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* If a were too big for an int, the library would throw an
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* exception. */
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b = a.toInt();
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BigInteger c(a); // Copy a BigInteger.
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// The int literal is converted to a BigInteger.
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BigInteger d(-314159265);
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/* This won't compile (at least on 32-bit machines) because the
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* number is too big to be a primitive integer literal, and
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* there's no such thing as a BigInteger literal. */
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//BigInteger e(3141592653589793238462643383279);
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// Instead you can convert the number from a string.
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std::string s("3141592653589793238462643383279");
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BigInteger f = stringToBigInteger(s);
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// You can convert the other way too.
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std::string s2 = bigIntegerToString(f);
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// f is implicitly stringified and sent to std::cout.
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std::cout << f << std::endl;
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/* Let's do some math! The library overloads most of the
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* mathematical operators (including assignment operators) to
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* work on BigIntegers. There are also ``copy-less''
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* operations; see `BigUnsigned.hh' for details. */
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// Arithmetic operators
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BigInteger g(314159), h(265);
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std::cout << (g + h) << '\n'
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<< (g - h) << '\n'
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<< (g * h) << '\n'
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<< (g / h) << '\n'
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<< (g % h) << std::endl;
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// Bitwise operators
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BigUnsigned i(0xFF0000FF), j(0x0000FFFF);
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// The library's << operator recognizes base flags.
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std::cout.flags(std::ios::hex | std::ios::showbase);
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std::cout << (i & j) << '\n'
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<< (i | j) << '\n'
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<< (i ^ j) << '\n'
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// Shift distances are ordinary unsigned ints.
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<< (j << 21) << '\n'
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<< (j >> 10) << '\n';
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std::cout.flags(std::ios::dec);
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// Let's do some heavy lifting and calculate powers of 314.
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int maxPower = 10;
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BigUnsigned x(1), big314(314);
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for (int power = 0; power <= maxPower; power++) {
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std::cout << "314^" << power << " = " << x << std::endl;
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x *= big314; // A BigInteger assignment operator
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}
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// Some big-integer algorithms (albeit on small integers).
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std::cout << gcd(BigUnsigned(60), 72) << '\n'
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<< modinv(BigUnsigned(7), 11) << '\n'
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<< modexp(BigUnsigned(314), 159, 2653) << std::endl;
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// Add your own code here to experiment with the library.
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} catch(char const* err) {
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std::cout << "The library threw an exception:\n"
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<< err << std::endl;
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}
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return 0;
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}
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/*
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The original sample program produces this output:
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3141592653589793238462643383279
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314424
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313894
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83252135
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1185
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134
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0xFF
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0xFF00FFFF
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0xFF00FF00
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0x1FFFE00000
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0x3F
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314^0 = 1
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314^1 = 314
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314^2 = 98596
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314^3 = 30959144
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314^4 = 9721171216
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314^5 = 3052447761824
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314^6 = 958468597212736
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314^7 = 300959139524799104
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314^8 = 94501169810786918656
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314^9 = 29673367320587092457984
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314^10 = 9317437338664347031806976
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12
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8
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1931
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*/
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