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sample.cc
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sample.cc
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// 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
*/