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<h1 class='fqn'><span class='in-band'>Trait <a href='../index.html'>std</a>::<wbr><a href='index.html'>fmt</a>::<wbr><a class='trait' href=''>Binary</a></span><span class='out-of-band'><span id='render-detail'>
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                [<span class='inner'>&#x2212;</span>]
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        </span><a id='src-34776' class='srclink' href='../../core/fmt/trait.Binary.html?gotosrc=34776' title='goto source code'>[src]</a></span></h1>
<pre class='rust trait'>pub trait Binary {
    fn <a href='#tymethod.fmt' class='fnname'>fmt</a>(&amp;self, &amp;mut <a class='struct' href='../../std/fmt/struct.Formatter.html' title='std::fmt::Formatter'>Formatter</a>) -&gt; <a class='enum' href='../../std/result/enum.Result.html' title='std::result::Result'>Result</a>&lt;<a class='primitive' href='../primitive.tuple.html'>()</a>, <a class='struct' href='../../std/fmt/struct.Error.html' title='std::fmt::Error'>Error</a>&gt;;
}</pre><div class='docblock'><p>Format trait for the <code>b</code> character.</p>

<p>The <code>Binary</code> trait should format its output as a number in binary.</p>

<p>The alternate flag, <code>#</code>, adds a <code>0b</code> in front of the output.</p>

<p>For more information on formatters, see <a href="../../std/fmt/index.html">the module-level documentation</a>.</p>

<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<p>Basic usage with <code>i32</code>:</p>
<span class='rusttest'>fn main() {
    let x = 42; // 42 is &#39;101010&#39; in binary
    
    assert_eq!(format!(&quot;{:b}&quot;, x), &quot;101010&quot;);
    assert_eq!(format!(&quot;{:#b}&quot;, x), &quot;0b101010&quot;);
    
}</span><pre class='rust rust-example-rendered'>
<span class='kw'>let</span> <span class='ident'>x</span> <span class='op'>=</span> <span class='number'>42</span>; <span class='comment'>// 42 is &#39;101010&#39; in binary</span>

<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='macro'>format</span><span class='macro'>!</span>(<span class='string'>&quot;{:b}&quot;</span>, <span class='ident'>x</span>), <span class='string'>&quot;101010&quot;</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='macro'>format</span><span class='macro'>!</span>(<span class='string'>&quot;{:#b}&quot;</span>, <span class='ident'>x</span>), <span class='string'>&quot;0b101010&quot;</span>);</pre>

<p>Implementing <code>Binary</code> on a type:</p>
<span class='rusttest'>fn main() {
    use std::fmt;
    
    struct Length(i32);
    
    impl fmt::Binary for Length {
        fn fmt(&amp;self, f: &amp;mut fmt::Formatter) -&gt; fmt::Result {
            let val = self.0;
    
            write!(f, &quot;{:b}&quot;, val) // delegate to i32&#39;s implementation
        }
    }
    
    let l = Length(107);
    
    println!(&quot;l as binary is: {:b}&quot;, l);
    
}</span><pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fmt</span>;

<span class='kw'>struct</span> <span class='ident'>Length</span>(<span class='ident'>i32</span>);

<span class='kw'>impl</span> <span class='ident'>fmt</span>::<span class='ident'>Binary</span> <span class='kw'>for</span> <span class='ident'>Length</span> {
    <span class='kw'>fn</span> <span class='ident'>fmt</span>(<span class='kw-2'>&amp;</span><span class='self'>self</span>, <span class='ident'>f</span>: <span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>fmt</span>::<span class='ident'>Formatter</span>) <span class='op'>-&gt;</span> <span class='ident'>fmt</span>::<span class='prelude-ty'>Result</span> {
        <span class='kw'>let</span> <span class='ident'>val</span> <span class='op'>=</span> <span class='self'>self</span>.<span class='number'>0</span>;

        <span class='macro'>write</span><span class='macro'>!</span>(<span class='ident'>f</span>, <span class='string'>&quot;{:b}&quot;</span>, <span class='ident'>val</span>) <span class='comment'>// delegate to i32&#39;s implementation</span>
    }
}

<span class='kw'>let</span> <span class='ident'>l</span> <span class='op'>=</span> <span class='ident'>Length</span>(<span class='number'>107</span>);

<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>&quot;l as binary is: {:b}&quot;</span>, <span class='ident'>l</span>);</pre>
</div>
            <h2 id='required-methods'>Required Methods</h2>
            <div class='methods'>
        <h3 id='tymethod.fmt' class='method stab '><code>fn <a href='#tymethod.fmt' class='fnname'>fmt</a>(&amp;self, &amp;mut <a class='struct' href='../../std/fmt/struct.Formatter.html' title='std::fmt::Formatter'>Formatter</a>) -&gt; <a class='enum' href='../../std/result/enum.Result.html' title='std::result::Result'>Result</a>&lt;<a class='primitive' href='../primitive.tuple.html'>()</a>, <a class='struct' href='../../std/fmt/struct.Error.html' title='std::fmt::Error'>Error</a>&gt;</code></h3><div class='docblock'><p>Formats the value using the given formatter.</p>
</div></div>
        <h2 id='implementors'>Implementors</h2>
        <ul class='item-list' id='implementors-list'>
    <li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.isize.html'>isize</a></code></li>
<li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.usize.html'>usize</a></code></li>
<li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.i8.html'>i8</a></code></li>
<li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.u8.html'>u8</a></code></li>
<li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.i16.html'>i16</a></code></li>
<li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.u16.html'>u16</a></code></li>
<li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.i32.html'>i32</a></code></li>
<li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.u32.html'>u32</a></code></li>
<li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.i64.html'>i64</a></code></li>
<li><code>impl <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for <a class='primitive' href='../primitive.u64.html'>u64</a></code></li>
<li><code>impl&lt;'a, T&gt; <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for &amp;'a T <span class='where'>where T: <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> + ?<a class='trait' href='../../std/marker/trait.Sized.html' title='std::marker::Sized'>Sized</a></span></code></li>
<li><code>impl&lt;'a, T&gt; <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> for &amp;'a mut T <span class='where'>where T: <a class='trait' href='../../std/fmt/trait.Binary.html' title='std::fmt::Binary'>Binary</a> + ?<a class='trait' href='../../std/marker/trait.Sized.html' title='std::marker::Sized'>Sized</a></span></code></li>
</ul><script type="text/javascript" async
                              src="../../implementors/core/fmt/trait.Binary.js">
                      </script></section>
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