53 lines
2.2 KiB
Plaintext
53 lines
2.2 KiB
Plaintext
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Copyright 2011 - 2020 John Maddock.
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Copyright 2013 - 2019 Paul A. Bristow.
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Copyright 2013 Christopher Kormanyos.
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt).
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]
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[section:gmp_int gmp_int]
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`#include <boost/multiprecision/gmp.hpp>`
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namespace boost{ namespace multiprecision{
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class gmp_int;
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typedef number<gmp_int > mpz_int;
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}} // namespaces
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The `gmp_int` back-end is used via the typedef `boost::multiprecision::mpz_int`. It acts as a thin wrapper around the [gmp] `mpz_t`
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to provide an integer type that is a drop-in replacement for the native C++ integer types, but with unlimited precision.
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As well as the usual conversions from arithmetic and string types, type `mpz_int` is copy constructible and assignable from:
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* The [gmp] native types: `mpf_t`, `mpz_t`, `mpq_t`.
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* Instances of `number<T>` that are wrappers around those types: `number<gmp_float<N> >`, `number<gmp_rational>`.
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It's also possible to access the underlying `mpz_t` via the `data()` member function of `gmp_int`.
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Things you should know when using this type:
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* No changes are made to the GMP library's global settings - so you can safely mix this type with
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existing code that uses [gmp].
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* Default constructed `gmp_int`s have the value zero (this is GMP's default behavior).
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* Formatted IO for this type does not support octal or hexadecimal notation for negative values,
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as a result performing formatted output on this type when the argument is negative and either of the flags
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`std::ios_base::oct` or `std::ios_base::hex` are set, will result in a `std::runtime_error` will be thrown.
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* Conversion from a string results in a `std::runtime_error` being thrown if the string can not be interpreted
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as a valid integer.
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* Division by zero results in a `std::overflow_error` being thrown.
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* Although this type is a wrapper around [gmp] it will work equally well with [mpir]. Indeed use of [mpir]
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is recommended on Win32.
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* This backend supports rvalue-references and is move-aware, making instantiations of `number` on this backend move aware.
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[h5 Example:]
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[mpz_eg]
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[endsect] [/section:gmp_int gmp_int]
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