[bigint/bigint.git] / sample.cc

/*
* Matt McCutchen's Big Integer Library
* http://mysite.verizon.net/mccutchen/bigint/
*/

/*
* This sample file demonstrates the most important features of the Big Integer Library.
*
* To get started quickly with the library, imitate the code in `main' below.
*
* If you want more detail or more speed or can't find a feature here,
* look in the appropriate source file.  This file shows only the more ``user-friendly'' features;
* the other features are messier but worth learning eventually.
*
* GO FORTH and play with many-digit numbers!  (c.f. The TeXbook.)
*/

// Standard libraries
#include <string>
#include <iostream>

// For the BigInteger class itself.
#include "BigInteger.hh"

// For the 4 routines `easy BI/BU <=> string' and `iostream' integration.
#include "BigIntegerUtils.hh"

int main() {
	try {
		BigInteger a; // a is 0
		int b = 535;
		
		a = b; // From int to BigInteger...
		b = a; // ...and back, no casts required!
		/*
		* If a were too big for an int you'd get a runtime exception.  The Big Integer Library
		* throws C-strings (that is, `const char *'s) when something goes wrong.  It's a good
		* idea to catch them; the `try/catch' construct wrapping all this code is an example
		* of how to do this.  Some C++ compilers need a special command-line option to compile
		* code that uses exceptions.
		*/
		
		BigInteger c(a); // Copy a BigInteger.
		
		BigInteger d(-314159265); // c is -314159265.  The `int' literal is converted to a BigInteger.
		
		// Ahem: that's too big to be an `int' literal (or even a `long' literal)!
		// Disillusion yourself now -- this won't compile.
		//BigInteger e(3141592653589793238462643383279);
		
		std::string s("3141592653589793238462643383279");
		BigInteger f = easyStringToBI(s);
		// Ah.  The string is converted to a BigInteger, and strings can be as long as you want.
		
		std::string s2 = easyBItoString(f); // You can convert the other way too.
		
		std::cout << f << std::endl; // f is stringified and send to std::cout.
		
		/*
		* Let's do some math!
		*
		* The Big Integer Library provides three kinds of operators:
		*
		* (1) Overloaded ``value'' operators: +, -, *, /, %, unary -.
		* Big-integer code using these operators looks identical to
		* code using the primitive integer types.  The operator takes
		* one or two BigInteger inputs and returns a BigInteger result,
		* which can then be assigned to a BigInteger variable or used
		* in an expression.
		*
		* (2) Overloaded assignment operators: +=, -=, *=, /=, %=,
		*     ++, --, flipSign.
		* Again, these are used on BigIntegers just like on ints.
		* They take one writable BigInteger that both provides an
		* operand and receives a result.  The first five also take
		* a second read-only operand.
		*
		* (3) ``Put-here'' operations: `add', `subtract', etc.
		* Use these if and only if you are concerned about performance.
		* They require fewer BigInteger copy-constructions and assignments
		* than do operators in (1) or (2).  Most take two read-only operands
		* and save the result in the invoked object `*this', whose previous
		* value is irrelevant.  `divideWithRemainder' is an exception.
		* <<< NOTE >>>: Put-here operations do not return a value: they don't need to!!
		*/
		
		BigInteger g(314159), h(265);
		// All five ``value'' operators
		std::cout << (g + h) << '\n' << (g - h) << '\n' << (g * h)
			<< '\n' << (g / h) << '\n' << (g % h) << std::endl;
		
		BigInteger i(5), j(10), k;
		// These two lines do the same thing: k is set to a BigInteger containing 15.
		k = i + j;
		k.add(i, j);
		
		// Let's do some heavy lifting.
		std::cout << "Powers of 3" << std::endl;
		std::cout << "How many do you want?" << std::endl;
		int maxPower;
		std::cin >> maxPower;
		
		BigUnsigned x(1), three(3);
		for (int power = 0; power <= maxPower; power++) {
			std::cout << "3^" << power << " = " << x << std::endl;
			x *= three; // A BigInteger assignment operator
		}
		
		std::cout << "There you go.  Goodbye." << std::endl;
		
	} catch(char const* err) {
		std::cout << "Sorry, the library threw an exception:\n"
			<< err << std::endl;
	}
	
	return 0;
}

/*
* Here is the output of a sample run of this sample program:

3141592653589793238462643383279
314424
313894
83252135
1185
134
Powers of 3
How many do you want?
2
3^0 = 1
3^1 = 3
3^2 = 9
There you go.  Goodbye.

*/
Commit	Line	Data
05780f4b MM	1	/*
	2	* Matt McCutchen's Big Integer Library
	3	* http://mysite.verizon.net/mccutchen/bigint/
	4	*/
	5
	6	/*
	7	* This sample file demonstrates the most important features of the Big Integer Library.
	8	*
	9	* To get started quickly with the library, imitate the code in `main' below.
	10	*
	11	* If you want more detail or more speed or can't find a feature here,
	12	* look in the appropriate source file. This file shows only the more ``user-friendly'' features;
	13	* the other features are messier but worth learning eventually.
	14	*
	15	* GO FORTH and play with many-digit numbers! (c.f. The TeXbook.)
	16	*/
	17
b3fe29df	18	// Standard libraries
05780f4b MM	19	#include <string>
	20	#include <iostream>
	21
b3fe29df MM	22	// For the BigInteger class itself.
	23	#include "BigInteger.hh"
	24
	25	// For the 4 routines `easy BI/BU <=> string' and `iostream' integration.
	26	#include "BigIntegerUtils.hh"
	27
05780f4b MM	28	int main() {
	29	try {
	30	BigInteger a; // a is 0
	31	int b = 535;
	32
b3fe29df	33	a = b; // From int to BigInteger...
05780f4b MM	34	b = a; // ...and back, no casts required!
	35	/*
	36	* If a were too big for an int you'd get a runtime exception. The Big Integer Library
	37	* throws C-strings (that is, `const char *'s) when something goes wrong. It's a good
b3fe29df MM	38	* idea to catch them; the `try/catch' construct wrapping all this code is an example
	39	* of how to do this. Some C++ compilers need a special command-line option to compile
	40	* code that uses exceptions.
05780f4b MM	41	*/
05780f4b MM	42
b3fe29df	43	BigInteger c(a); // Copy a BigInteger.
05780f4b MM	44
	45	BigInteger d(-314159265); // c is -314159265. The `int' literal is converted to a BigInteger.
	46
	47	// Ahem: that's too big to be an `int' literal (or even a `long' literal)!
	48	// Disillusion yourself now -- this won't compile.
	49	//BigInteger e(3141592653589793238462643383279);
	50
	51	std::string s("3141592653589793238462643383279");
	52	BigInteger f = easyStringToBI(s);
	53	// Ah. The string is converted to a BigInteger, and strings can be as long as you want.
	54
	55	std::string s2 = easyBItoString(f); // You can convert the other way too.
	56
	57	std::cout << f << std::endl; // f is stringified and send to std::cout.
	58
	59	/*
	60	* Let's do some math!
	61	*
	62	* The Big Integer Library provides three kinds of operators:
	63	*
	64	* (1) Overloaded ``value'' operators: +, -, *, /, %, unary -.
	65	* Big-integer code using these operators looks identical to
	66	* code using the primitive integer types. The operator takes
	67	* one or two BigInteger inputs and returns a BigInteger result,
	68	* which can then be assigned to a BigInteger variable or used
	69	* in an expression.
	70	*
	71	* (2) Overloaded assignment operators: +=, -=, *=, /=, %=,
	72	* ++, --, flipSign.
	73	* Again, these are used on BigIntegers just like on ints.
	74	* They take one writable BigInteger that both provides an
	75	* operand and receives a result. The first five also take
	76	* a second read-only operand.
	77	*
	78	* (3) ``Put-here'' operations: `add', `subtract', etc.
	79	* Use these if and only if you are concerned about performance.
	80	* They require fewer BigInteger copy-constructions and assignments
	81	* than do operators in (1) or (2). Most take two read-only operands
	82	* and save the result in the invoked object `*this', whose previous
	83	* value is irrelevant. `divideWithRemainder' is an exception.
	84	* <<< NOTE >>>: Put-here operations do not return a value: they don't need to!!
	85	*/
	86
	87	BigInteger g(314159), h(265);
	88	// All five ``value'' operators
	89	std::cout << (g + h) << '\n' << (g - h) << '\n' << (g * h)
	90	<< '\n' << (g / h) << '\n' << (g % h) << std::endl;
	91
	92	BigInteger i(5), j(10), k;
	93	// These two lines do the same thing: k is set to a BigInteger containing 15.
	94	k = i + j;
	95	k.add(i, j);
	96
	97	// Let's do some heavy lifting.
	98	std::cout << "Powers of 3" << std::endl;
	99	std::cout << "How many do you want?" << std::endl;
	100	int maxPower;
	101	std::cin >> maxPower;
	102
	103	BigUnsigned x(1), three(3);
	104	for (int power = 0; power <= maxPower; power++) {
	105	std::cout << "3^" << power << " = " << x << std::endl;
	106	x *= three; // A BigInteger assignment operator
	107	}
108
109	std::cout << "There you go. Goodbye." << std::endl;
110
b3fe29df	111	} catch(char const* err) {
05780f4b MM	112	std::cout << "Sorry, the library threw an exception:\n"
	113	<< err << std::endl;
	114	}
b3fe29df	115
05780f4b MM	116	return 0;
	117	}
	118
	119	/*
	120	* Here is the output of a sample run of this sample program:
	121
	122	3141592653589793238462643383279
	123	314424
	124	313894
	125	83252135
	126	1185
	127	134
	128	Powers of 3
	129	How many do you want?
	130	2
	131	3^0 = 1
	132	3^1 = 3
	133	3^2 = 9
	134	There you go. Goodbye.
	135
	136	*/