<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `UpperExp` trait in crate `std`."><meta name="keywords" content="rust, rustlang, rust-lang, UpperExp"><title>std::fmt::UpperExp - Rust</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script src="../../storage.js"></script><link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"></head><body class="rustdoc trait"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../std/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a><p class='location'>Trait UpperExp</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#required-methods">Required Methods</a><div class="sidebar-links"><a href="#tymethod.fmt">fmt</a></div><a class="sidebar-title" href="#implementors">Implementors</a></div><p class='location'><a href='../index.html'>std</a>::<wbr><a href='index.html'>fmt</a></p><script>window.sidebarCurrent = {name: 'UpperExp', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><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=''>UpperExp</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='../../src/core/fmt/mod.rs.html#984-988' title='goto source code'>[src]</a></span></h1><div class="docblock type-decl"><pre class='rust trait'>pub trait UpperExp { fn <a href='#tymethod.fmt' class='fnname'>fmt</a>(&self, f: &mut <a class="struct" href="../../std/fmt/struct.Formatter.html" title="struct std::fmt::Formatter">Formatter</a>) -> <a class="enum" href="../../std/result/enum.Result.html" title="enum std::result::Result">Result</a><<a class="primitive" href="../primitive.unit.html">()</a>, <a class="struct" href="../../std/fmt/struct.Error.html" title="struct std::fmt::Error">Error</a>>; }</pre></div><div class='docblock'><p><code>E</code> formatting.</p> <p>The <code>UpperExp</code> trait should format its output in scientific notation with an upper-case <code>E</code>.</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>f32</code>:</p> <pre class="rust rust-example-rendered"> <span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="number">42.0</span>; <span class="comment">// 42.0 is '4.2E1' in scientific notation</span> <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="macro">format</span><span class="macro">!</span>(<span class="string">"{:E}"</span>, <span class="ident">x</span>), <span class="string">"4.2E1"</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Alet%20x%20%3D%2042.0%3B%20%2F%2F%2042.0%20is%20'4.2E1'%20in%20scientific%20notation%0A%0Aassert_eq!(format!(%22%7B%3AE%7D%22%2C%20x)%2C%20%224.2E1%22)%3B%0A%7D">Run</a></pre> <p>Implementing <code>UpperExp</code> on a type:</p> <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">UpperExp</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">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></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">"{}E1"</span>, <span class="ident">val</span> <span class="op">/</span> <span class="number">10</span>) } } <span class="kw">let</span> <span class="ident">l</span> <span class="op">=</span> <span class="ident">Length</span>(<span class="number">100</span>); <span class="macro">println</span><span class="macro">!</span>(<span class="string">"l in scientific notation is: {:E}"</span>, <span class="ident">l</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Ause%20std%3A%3Afmt%3B%0A%0Astruct%20Length(i32)%3B%0A%0Aimpl%20fmt%3A%3AUpperExp%20for%20Length%20%7B%0A%20%20%20%20fn%20fmt(%26self%2C%20f%3A%20%26mut%20fmt%3A%3AFormatter)%20-%3E%20fmt%3A%3AResult%20%7B%0A%20%20%20%20%20%20%20%20let%20val%20%3D%20self.0%3B%0A%20%20%20%20%20%20%20%20write!(f%2C%20%22%7B%7DE1%22%2C%20val%20%2F%2010)%0A%20%20%20%20%7D%0A%7D%0A%0Alet%20l%20%3D%20Length(100)%3B%0A%0Aprintln!(%22l%20in%20scientific%20notation%20is%3A%20%7B%3AE%7D%22%2C%20l)%3B%0A%7D">Run</a></pre> </div> <h2 id='required-methods' class='small-section-header'> Required Methods<a href='#required-methods' class='anchor'></a> </h2> <div class='methods'> <h3 id='tymethod.fmt' class='method'><span id='fmt.v' class='invisible'><code>fn <a href='#tymethod.fmt' class='fnname'>fmt</a>(&self, f: &mut <a class="struct" href="../../std/fmt/struct.Formatter.html" title="struct std::fmt::Formatter">Formatter</a>) -> <a class="enum" href="../../std/result/enum.Result.html" title="enum std::result::Result">Result</a><<a class="primitive" href="../primitive.unit.html">()</a>, <a class="struct" href="../../std/fmt/struct.Error.html" title="struct std::fmt::Error">Error</a>></code></span></h3><div class='docblock'><p>Formats the value using the given formatter.</p> </div></div> <h2 id='implementors' class='small-section-header'> Implementors<a href='#implementors' class='anchor'></a> </h2> <ul class='item-list' id='implementors-list'> <li><table class='table-display'><tbody><tr><td><code>impl UpperExp for <a class="primitive" href="../primitive.f32.html">f32</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/core/fmt/float.rs.html#148-152' title='goto source code'>[src]</a></div></td></tr></tbody></table></li> <li><table class='table-display'><tbody><tr><td><code>impl<'a, T> UpperExp for <a class="primitive" href="../primitive.reference.html">&'a </a>T <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/fmt/trait.UpperExp.html" title="trait std::fmt::UpperExp">UpperExp</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>, </span></code><td><div class='out-of-band'><a class='srclink' href='../../src/core/fmt/mod.rs.html#1773-1775' title='goto source code'>[src]</a></div></td></tr></tbody></table></li> <li><table class='table-display'><tbody><tr><td><code>impl<'a, T> UpperExp for <a class="primitive" href="../primitive.reference.html">&'a mut </a>T <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/fmt/trait.UpperExp.html" title="trait std::fmt::UpperExp">UpperExp</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>, </span></code><td><div class='out-of-band'><a class='srclink' href='../../src/core/fmt/mod.rs.html#1777-1779' title='goto source code'>[src]</a></div></td></tr></tbody></table></li> <li><table class='table-display'><tbody><tr><td><code>impl UpperExp for <a class="primitive" href="../primitive.f64.html">f64</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/core/fmt/float.rs.html#148-152' title='goto source code'>[src]</a></div></td></tr></tbody></table></li> </ul><script type="text/javascript">window.inlined_types=new Set([]);</script><script type="text/javascript" async src="../../implementors/core/fmt/trait.UpperExp.js"> </script></section><section id="search" class="content hidden"></section><section class="footer"></section><aside id="help" class="hidden"><div><h1 class="hidden">Help</h1><div class="shortcuts"><h2>Keyboard Shortcuts</h2><dl><dt><kbd>?</kbd></dt><dd>Show this help dialog</dd><dt><kbd>S</kbd></dt><dd>Focus the search field</dd><dt><kbd>↑</kbd></dt><dd>Move up in search 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