X-Git-Url: https://mattmccutchen.net/bigint/bigint.git/blobdiff_plain/05780f4b578d6ae054be0b19b8498d32a4f16c60..00c6448a6c5fc7a68427ca1dc3f5f523563e1041:/sample.cc diff --git a/sample.cc b/sample.cc index 58023a6..9a75175 100644 --- a/sample.cc +++ b/sample.cc @@ -1,118 +1,95 @@ /* * 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.) +* Sample program demonstrating the most important features of the Big +* Integer Library */ -#include "BigUnsigned.hh" -#include "BigInteger.hh" -#include "BigIntegerUtils.hh" - +// Standard libraries #include #include +// 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 BigUnsigned... + 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. Some C++ compilers need a special command-line option to compile - * code that uses throw/catch. + * 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 them. + BigInteger c(a); // Copy a BigInteger. - BigInteger d(-314159265); // c is -314159265. The `int' literal is converted to a BigInteger. + // d is -314159265. The `int' literal is converted to a + // BigInteger. + BigInteger d(-314159265); - // Ahem: that's too big to be an `int' literal (or even a `long' literal)! - // Disillusion yourself now -- this won't compile. + // This won't compile because the number is too big to be an + // integer literal. //BigInteger e(3141592653589793238462643383279); + // Instead you can convert the number from a string. 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. + // You can convert the other way too. + std::string s2 = easyBItoString(f); - std::cout << f << std::endl; // f is stringified and send to std::cout. + // f is stringified and send to std::cout. + std::cout << f << std::endl; /* * 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!! + * The Big Integer Library provides lots of overloaded operators + * and corresponding assignment operators. So you can do `a + b' + * with BigIntegers just as with normal integers. The named + * methods `add', `divideWithRemainder', etc. are more advanced + * ``put-here operations''; see `BigUnsigned.hh' for details. */ - BigInteger g(314159), h(265); - // All five ``value'' operators + // All five ``return-by-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); + // 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 << "3^" << power << " = " << x << std::endl; - x *= three; // A BigInteger assignment operator + std::cout << "314^" << power << " = " << x << std::endl; + x *= big314; // A BigInteger assignment operator } - std::cout << "There you go. Goodbye." << std::endl; + /* + * If you want to experiment with the library, + * you can add your own test code here. + */ + // std::cout << "Beginning of custom test code:\n" << std::endl; - } catch(char const* err){ - std::cout << "Sorry, the library threw an exception:\n" + } catch(char const* err) { + std::cout << "The library threw an exception:\n" << err << std::endl; } + return 0; } /* -* Here is the output of a sample run of this sample program: +Running the sample program produces this output: 3141592653589793238462643383279 314424 @@ -120,12 +97,16 @@ int main() { 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. +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 */