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<p class='location'><a href='index.html'>rand</a></p><script>window.sidebarCurrent = {name: 'random', ty: 'fn', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<section id='main' class="content fn">
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<h1 class='fqn'><span class='in-band'>Function <a href='index.html'>rand</a>::<wbr><a class='fn' href=''>random</a></span><span class='out-of-band'><span id='render-detail'>
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</span><a id='src-1746' class='srclink' href='../src/rand/lib.rs.html#945-947' title='goto source code'>[src]</a></span></h1>
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<pre class='rust fn'>pub fn random<T: <a class='trait' href='../rand/trait.Rand.html' title='rand::Rand'>Rand</a>>() -> T</pre><div class='docblock'><p>Generates a random value using the thread-local random number generator.</p>
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<p><code>random()</code> can generate various types of random things, and so may require
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type hinting to generate the specific type you want.</p>
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<p>This function uses the thread local random number generator. This means
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that if you're calling <code>random()</code> in a loop, caching the generator can
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increase performance. An example is shown below.</p>
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<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
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<pre class='rust rust-example-rendered'>
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<span class='kw'>let</span> <span class='ident'>x</span> <span class='op'>=</span> <span class='ident'>rand</span>::<span class='ident'>random</span>::<span class='op'><</span><span class='ident'>u8</span><span class='op'>></span>();
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<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"{}"</span>, <span class='ident'>x</span>);
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<span class='kw'>let</span> <span class='ident'>y</span> <span class='op'>=</span> <span class='ident'>rand</span>::<span class='ident'>random</span>::<span class='op'><</span><span class='ident'>f64</span><span class='op'>></span>();
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<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"{}"</span>, <span class='ident'>y</span>);
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<span class='kw'>if</span> <span class='ident'>rand</span>::<span class='ident'>random</span>() { <span class='comment'>// generates a boolean</span>
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<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"Better lucky than good!"</span>);
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}</pre>
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<p>Caching the thread local random number generator:</p>
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<pre class='rust rust-example-rendered'>
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<span class='kw'>use</span> <span class='ident'>rand</span>::<span class='ident'>Rng</span>;
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<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>v</span> <span class='op'>=</span> <span class='macro'>vec</span><span class='macro'>!</span>[<span class='number'>1</span>, <span class='number'>2</span>, <span class='number'>3</span>];
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<span class='kw'>for</span> <span class='ident'>x</span> <span class='kw'>in</span> <span class='ident'>v</span>.<span class='ident'>iter_mut</span>() {
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<span class='op'>*</span><span class='ident'>x</span> <span class='op'>=</span> <span class='ident'>rand</span>::<span class='ident'>random</span>()
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}
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<span class='comment'>// would be faster as</span>
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<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>();
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<span class='kw'>for</span> <span class='ident'>x</span> <span class='kw'>in</span> <span class='ident'>v</span>.<span class='ident'>iter_mut</span>() {
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<span class='op'>*</span><span class='ident'>x</span> <span class='op'>=</span> <span class='ident'>rng</span>.<span class='ident'>gen</span>();
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}</pre>
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