Matt McCutchen's Web Site - bigint/bigint.git/blame_incremental

... / ...

Commit	Line	Data
	1	// Sample program demonstrating the use of the Big Integer Library.
	2
	3	// Standard libraries
	4	#include <string>
	5	#include <iostream>
	6
	7	// `BigIntegerLibrary.hh' includes all of the library headers.
	8	#include "BigIntegerLibrary.hh"
	9
	10	int main() {
	11	/* The library throws `const char *' error messages when things go
	12	* wrong. It's a good idea to catch them using a `try' block like this
	13	* one. Your C++ compiler might need a command-line option to compile
	14	* code that uses exceptions. */
	15	try {
	16	BigInteger a; // a is 0
	17	int b = 535;
	18
	19	/* Any primitive integer can be converted implicitly to a
	20	* BigInteger. */
	21	a = b;
	22
	23	/* The reverse conversion requires a method call (implicit
	24	* conversions were previously supported but caused trouble).
	25	* If a were too big for an int, the library would throw an
	26	* exception. */
	27	b = a.toInt();
	28
	29	BigInteger c(a); // Copy a BigInteger.
	30
	31	// The int literal is converted to a BigInteger.
	32	BigInteger d(-314159265);
	33
	34	/* This won't compile (at least on 32-bit machines) because the
	35	* number is too big to be a primitive integer literal, and
	36	* there's no such thing as a BigInteger literal. */
	37	//BigInteger e(3141592653589793238462643383279);
	38
	39	// Instead you can convert the number from a string.
	40	std::string s("3141592653589793238462643383279");
	41	BigInteger f = stringToBigInteger(s);
	42
	43	// You can convert the other way too.
	44	std::string s2 = bigIntegerToString(f);
	45
	46	// f is implicitly stringified and sent to std::cout.
	47	std::cout << f << std::endl;
	48
	49	/* Let's do some math! The library overloads most of the
	50	* mathematical operators (including assignment operators) to
	51	* work on BigIntegers. There are also ``copy-less''
	52	* operations; see `BigUnsigned.hh' for details. */
	53
	54	// Arithmetic operators
	55	BigInteger g(314159), h(265);
	56	std::cout << (g + h) << '\n'
	57	<< (g - h) << '\n'
	58	<< (g * h) << '\n'
	59	<< (g / h) << '\n'
	60	<< (g % h) << std::endl;
	61
	62	// Bitwise operators
	63	BigUnsigned i(0xFF0000FF), j(0x0000FFFF);
	64	// The library's << operator recognizes base flags.
	65	std::cout.flags(std::ios::hex \| std::ios::showbase);
	66	std::cout << (i & j) << '\n'
	67	<< (i \| j) << '\n'
	68	<< (i ^ j) << '\n'
	69	// Shift distances are ordinary unsigned ints.
	70	<< (j << 21) << '\n'
	71	<< (j >> 10) << '\n';
	72	std::cout.flags(std::ios::dec);
	73
	74	// Let's do some heavy lifting and calculate powers of 314.
	75	int maxPower = 10;
	76	BigUnsigned x(1), big314(314);
	77	for (int power = 0; power <= maxPower; power++) {
	78	std::cout << "314^" << power << " = " << x << std::endl;
	79	x *= big314; // A BigInteger assignment operator
	80	}
	81
	82	// Some big-integer algorithms (albeit on small integers).
	83	std::cout << gcd(BigUnsigned(60), 72) << '\n'
	84	<< modinv(BigUnsigned(7), 11) << '\n'
	85	<< modexp(BigUnsigned(314), 159, 2653) << std::endl;
	86
	87	// Add your own code here to experiment with the library.
	88	} catch(char const* err) {
	89	std::cout << "The library threw an exception:\n"
	90	<< err << std::endl;
	91	}
	92
	93	return 0;
	94	}
	95
	96	/*
	97	The original sample program produces this output:
	98
	99	3141592653589793238462643383279
	100	314424
	101	313894
	102	83252135
	103	1185
	104	134
	105	0xFF
	106	0xFF00FFFF
	107	0xFF00FF00
	108	0x1FFFE00000
	109	0x3F
	110	314^0 = 1
	111	314^1 = 314
	112	314^2 = 98596
	113	314^3 = 30959144
	114	314^4 = 9721171216
	115	314^5 = 3052447761824
	116	314^6 = 958468597212736
	117	314^7 = 300959139524799104
	118	314^8 = 94501169810786918656
	119	314^9 = 29673367320587092457984
	120	314^10 = 9317437338664347031806976
	121	12
	122	8
	123	1931
	124
	125	*/