(C++) Hello BigInt

February 24, 2017 · View on GitHub

'Hello BigInt' is like a 'Hello World' program, except for additionally using the BigInt library.

Running Hello BigInt depends on your operating system or system environment:

The code of Hello BigInt is the sample code given by BigInt's author on the BigInt website. This code is shown below.

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