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<h1 class='fqn'><span class='in-band'>Crate <a class='mod' href=''>num_bigint</a></span><span class='out-of-band'><span id='render-detail'>
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</span><a id='src-0' class='srclink' href='../src/num_bigint/lib.rs.html#11-5156' title='goto source code'>[src]</a></span></h1>
<div class='docblock'><p>A Big integer (signed version: <code>BigInt</code>, unsigned version: <code>BigUint</code>).</p>
<p>A <code>BigUint</code> is represented as a vector of <code>BigDigit</code>s.
A <code>BigInt</code> is a combination of <code>BigUint</code> and <code>Sign</code>.</p>
<p>Common numerical operations are overloaded, so we can treat them
the same way we treat other numbers.</p>
<h2 id='example' class='section-header'><a href='#example'>Example</a></h2>
<pre class='rust rust-example-rendered'>
<span class='kw'>extern</span> <span class='kw'>crate</span> <span class='ident'>num_bigint</span>;
<span class='kw'>extern</span> <span class='kw'>crate</span> <span class='ident'>num_traits</span>;
<span class='kw'>use</span> <span class='ident'>num_bigint</span>::<span class='ident'>BigUint</span>;
<span class='kw'>use</span> <span class='ident'>num_traits</span>::{<span class='ident'>Zero</span>, <span class='ident'>One</span>};
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>mem</span>::<span class='ident'>replace</span>;
<span class='comment'>// Calculate large fibonacci numbers.</span>
<span class='kw'>fn</span> <span class='ident'>fib</span>(<span class='ident'>n</span>: <span class='ident'>usize</span>) <span class='op'>-></span> <span class='ident'>BigUint</span> {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f0</span>: <span class='ident'>BigUint</span> <span class='op'>=</span> <span class='ident'>Zero</span>::<span class='ident'>zero</span>();
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f1</span>: <span class='ident'>BigUint</span> <span class='op'>=</span> <span class='ident'>One</span>::<span class='ident'>one</span>();
<span class='kw'>for</span> _ <span class='kw'>in</span> <span class='number'>0</span>..<span class='ident'>n</span> {
<span class='kw'>let</span> <span class='ident'>f2</span> <span class='op'>=</span> <span class='ident'>f0</span> <span class='op'>+</span> <span class='kw-2'>&</span><span class='ident'>f1</span>;
<span class='comment'>// This is a low cost way of swapping f0 with f1 and f1 with f2.</span>
<span class='ident'>f0</span> <span class='op'>=</span> <span class='ident'>replace</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>f1</span>, <span class='ident'>f2</span>);
}
<span class='ident'>f0</span>
}
<span class='comment'>// This is a very large number.</span>
<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"fib(1000) = {}"</span>, <span class='ident'>fib</span>(<span class='number'>1000</span>));<a class='test-arrow' target='_blank' href=''>Run</a></pre>
<p>It's easy to generate large random numbers:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>extern</span> <span class='kw'>crate</span> <span class='ident'>rand</span>;
<span class='kw'>extern</span> <span class='kw'>crate</span> <span class='ident'>num_bigint</span> <span class='kw'>as</span> <span class='ident'>bigint</span>;
<span class='kw'>use</span> <span class='ident'>bigint</span>::{<span class='ident'>ToBigInt</span>, <span class='ident'>RandBigInt</span>};
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>rng</span> <span class='op'>=</span> <span class='ident'>rand</span>::<span class='ident'>thread_rng</span>();
<span class='kw'>let</span> <span class='ident'>a</span> <span class='op'>=</span> <span class='ident'>rng</span>.<span class='ident'>gen_bigint</span>(<span class='number'>1000</span>);
<span class='kw'>let</span> <span class='ident'>low</span> <span class='op'>=</span> <span class='op'>-</span><span class='number'>10000</span>.<span class='ident'>to_bigint</span>().<span class='ident'>unwrap</span>();
<span class='kw'>let</span> <span class='ident'>high</span> <span class='op'>=</span> <span class='number'>10000</span>.<span class='ident'>to_bigint</span>().<span class='ident'>unwrap</span>();
<span class='kw'>let</span> <span class='ident'>b</span> <span class='op'>=</span> <span class='ident'>rng</span>.<span class='ident'>gen_bigint_range</span>(<span class='kw-2'>&</span><span class='ident'>low</span>, <span class='kw-2'>&</span><span class='ident'>high</span>);
<span class='comment'>// Probably an even larger number.</span>
<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"{}"</span>, <span class='ident'>a</span> <span class='op'>*</span> <span class='ident'>b</span>);
<a class='test-arrow' target='_blank' href=''>Run</a></pre>
</div><h2 id='modules' class='section-header'><a href="#modules">Modules</a></h2>
<table>
<tr class=' module-item'>
<td><a class='mod' href='big_digit/index.html'
title='num_bigint::big_digit'>big_digit</a></td>
<td class='docblock-short'>
</td>
</tr></table><h2 id='structs' class='section-header'><a href="#structs">Structs</a></h2>
<table>
<tr class=' module-item'>
<td><a class='struct' href='struct.BigInt.html'
title='num_bigint::BigInt'>BigInt</a></td>
<td class='docblock-short'>
<p>A big signed integer type.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='struct' href='struct.BigUint.html'
title='num_bigint::BigUint'>BigUint</a></td>
<td class='docblock-short'>
<p>A big unsigned integer type.</p>
</td>
</tr></table><h2 id='enums' class='section-header'><a href="#enums">Enums</a></h2>
<table>
<tr class=' module-item'>
<td><a class='enum' href='enum.ParseBigIntError.html'
title='num_bigint::ParseBigIntError'>ParseBigIntError</a></td>
<td class='docblock-short'>
</td>
</tr>
<tr class=' module-item'>
<td><a class='enum' href='enum.Sign.html'
title='num_bigint::Sign'>Sign</a></td>
<td class='docblock-short'>
<p>A Sign is a <code>BigInt</code>'s composing element.</p>
</td>
</tr></table><h2 id='constants' class='section-header'><a href="#constants">Constants</a></h2>
<table>
<tr class=' module-item'>
<td><a class='constant' href='constant.ZERO_BIG_DIGIT.html'
title='num_bigint::ZERO_BIG_DIGIT'>ZERO_BIG_DIGIT</a></td>
<td class='docblock-short'>
</td>
</tr></table><h2 id='traits' class='section-header'><a href="#traits">Traits</a></h2>
<table>
<tr class=' module-item'>
<td><a class='trait' href='trait.RandBigInt.html'
title='num_bigint::RandBigInt'>RandBigInt</a></td>
<td class='docblock-short'>
</td>
</tr>
<tr class=' module-item'>
<td><a class='trait' href='trait.ToBigInt.html'
title='num_bigint::ToBigInt'>ToBigInt</a></td>
<td class='docblock-short'>
<p>A generic trait for converting a value to a <code>BigInt</code>.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='trait' href='trait.ToBigUint.html'
title='num_bigint::ToBigUint'>ToBigUint</a></td>
<td class='docblock-short'>
<p>A generic trait for converting a value to a <code>BigUint</code>.</p>
</td>
</tr></table><h2 id='types' class='section-header'><a href="#types">Type Definitions</a></h2>
<table>
<tr class=' module-item'>
<td><a class='type' href='type.BigDigit.html'
title='num_bigint::BigDigit'>BigDigit</a></td>
<td class='docblock-short'>
<p>A <code>BigDigit</code> is a <code>BigUint</code>'s composing element.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='type' href='type.DoubleBigDigit.html'
title='num_bigint::DoubleBigDigit'>DoubleBigDigit</a></td>
<td class='docblock-short'>
<p>A <code>DoubleBigDigit</code> is the internal type used to do the computations. Its
size is the double of the size of <code>BigDigit</code>.</p>
</td>
</tr></table></section>
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