2016-05-10 15:03:32 -04:00
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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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2016-05-10 23:34:09 -04:00
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2016-05-10 15:03:32 -04:00
< 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 >
< p > < code > random()< / code > can generate various types of random things, and so may require
type hinting to generate the specific type you want.< / p >
< p > This function uses the thread local random number generator. This means
that if you' re calling < code > random()< / code > in a loop, caching the generator can
increase performance. An example is shown below.< / p >
< h1 id = 'examples' class = 'section-header' > < a href = '#examples' > Examples< / a > < / h1 >
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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 > ();
< span class = 'macro' > println< / span > < span class = 'macro' > !< / span > (< span class = 'string' > " {}" < / span > , < span class = 'ident' > x< / span > );
< 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 > ();
< span class = 'macro' > println< / span > < span class = 'macro' > !< / span > (< span class = 'string' > " {}" < / span > , < span class = 'ident' > y< / span > );
< span class = 'kw' > if< / span > < span class = 'ident' > rand< / span > ::< span class = 'ident' > random< / span > () { < span class = 'comment' > // generates a boolean< / span >
< span class = 'macro' > println< / span > < span class = 'macro' > !< / span > (< span class = 'string' > " Better lucky than good!" < / span > );
}< / pre >
< p > Caching the thread local random number generator:< / p >
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< span class = 'kw' > use< / span > < span class = 'ident' > rand< / span > ::< span class = 'ident' > Rng< / span > ;
< 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 > ];
< 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 > () {
< span class = 'op' > *< / span > < span class = 'ident' > x< / span > < span class = 'op' > =< / span > < span class = 'ident' > rand< / span > ::< span class = 'ident' > random< / span > ()
}
< span class = 'comment' > // would be faster as< / 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' > for< / span > < span class = 'ident' > x< / span > < span class = 'kw' > in< / span > < span class = 'ident' > v< / span > .< span class = 'ident' > iter_mut< / span > () {
< 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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