<!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 `Arguments` struct in crate `std`."><meta name="keywords" content="rust, rustlang, rust-lang, Arguments"><title>std::fmt::Arguments - 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 struct"><!--[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'>Struct Arguments</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#implementations">Trait Implementations</a><div class="sidebar-links"><a href="#impl-Display">Display</a><a href="#impl-Debug">Debug</a><a href="#impl-Clone">Clone</a><a href="#impl-Copy">Copy</a></div><a class="sidebar-title" href="#synthetic-implementations">Auto Trait Implementations</a><div class="sidebar-links"><a href="#impl-Send">!Send</a><a href="#impl-Sync">!Sync</a></div></div><p class='location'><a href='../index.html'>std</a>::<wbr><a href='index.html'>fmt</a></p><script>window.sidebarCurrent = {name: 'Arguments', ty: 'struct', 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'>Struct <a href='../index.html'>std</a>::<wbr><a href='index.html'>fmt</a>::<wbr><a class="struct" href=''>Arguments</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#426-436' title='goto source code'>[src]</a></span></h1><div class="docblock type-decl"><pre class='rust struct'>pub struct Arguments<'a> { /* fields omitted */ }</pre></div><div class='docblock'><p>This structure represents a safely precompiled version of a format string
and its arguments. This cannot be generated at runtime because it cannot
safely be done, so no constructors are given and the fields are private
to prevent modification.</p>
<p>The <a href="../../std/macro.format_args.html"><code>format_args!</code></a> macro will safely create an instance of this structure.
The macro validates the format string at compile-time so usage of the
<a href="../../std/fmt/fn.write.html"><code>write</code></a> and <a href="../../std/fmt/fn.format.html"><code>format</code></a> functions can be safely performed.</p>
<p>You can use the <code>Arguments<'a></code> that <a href="../../std/macro.format_args.html"><code>format_args!</code></a> returns in <code>Debug</code>
and <code>Display</code> contexts as seen below. The example also shows that <code>Debug</code>
and <code>Display</code> format to the same thing: the interpolated format string
in <code>format_args!</code>.</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">debug</span> <span class="op">=</span> <span class="macro">format</span><span class="macro">!</span>(<span class="string">"{:?}"</span>, <span class="macro">format_args</span><span class="macro">!</span>(<span class="string">"{} foo {:?}"</span>, <span class="number">1</span>, <span class="number">2</span>));
<span class="kw">let</span> <span class="ident">display</span> <span class="op">=</span> <span class="macro">format</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="macro">format_args</span><span class="macro">!</span>(<span class="string">"{} foo {:?}"</span>, <span class="number">1</span>, <span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">"1 foo 2"</span>, <span class="ident">display</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">display</span>, <span class="ident">debug</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Alet%20debug%20%3D%20format!(%22%7B%3A%3F%7D%22%2C%20format_args!(%22%7B%7D%20foo%20%7B%3A%3F%7D%22%2C%201%2C%202))%3B%0Alet%20display%20%3D%20format!(%22%7B%7D%22%2C%20format_args!(%22%7B%7D%20foo%20%7B%3A%3F%7D%22%2C%201%2C%202))%3B%0Aassert_eq!(%221%20foo%202%22%2C%20display)%3B%0Aassert_eq!(display%2C%20debug)%3B%0A%7D">Run</a></pre>
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<div id='implementations-list'><h3 id='impl-Display' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl<'a> <a class="trait" href="../../std/fmt/trait.Display.html" title="trait std::fmt::Display">Display</a> for <a class="struct" href="../../std/fmt/struct.Arguments.html" title="struct std::fmt::Arguments">Arguments</a><'a></code><a href='#impl-Display' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/fmt/mod.rs.html#446-450' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/fmt/trait.Display.html#tymethod.fmt' class='fnname'>fmt</a>(&self, fmt: &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></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/fmt/mod.rs.html#447-449' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Formats the value using the given formatter. <a href="../../std/fmt/trait.Display.html#tymethod.fmt">Read more</a></p>
</div></div><h3 id='impl-Debug' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl<'a> <a class="trait" href="../../std/fmt/trait.Debug.html" title="trait std::fmt::Debug">Debug</a> for <a class="struct" href="../../std/fmt/struct.Arguments.html" title="struct std::fmt::Arguments">Arguments</a><'a></code><a href='#impl-Debug' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/fmt/mod.rs.html#439-443' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.fmt-1' class="method"><span id='fmt.v-1' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&self, fmt: &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></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/fmt/mod.rs.html#440-442' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Formats the value using the given formatter. <a href="../../std/fmt/trait.Debug.html#tymethod.fmt">Read more</a></p>
</div></div><h3 id='impl-Clone' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl<'a> <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a> for <a class="struct" href="../../std/fmt/struct.Arguments.html" title="struct std::fmt::Arguments">Arguments</a><'a></code><a href='#impl-Clone' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/fmt/mod.rs.html#425' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.clone' class="method"><span id='clone.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/clone/trait.Clone.html#tymethod.clone' class='fnname'>clone</a>(&self) -> <a class="struct" href="../../std/fmt/struct.Arguments.html" title="struct std::fmt::Arguments">Arguments</a><'a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/fmt/mod.rs.html#425' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns a copy of the value. <a href="../../std/clone/trait.Clone.html#tymethod.clone">Read more</a></p>
</div><h4 id='method.clone_from' class="method"><span id='clone_from.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/clone/trait.Clone.html#method.clone_from' class='fnname'>clone_from</a>(&mut self, source: <a class="primitive" href="../primitive.reference.html">&</a>Self)</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/clone.rs.html#130-132' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Performs copy-assignment from <code>source</code>. <a href="../../std/clone/trait.Clone.html#method.clone_from">Read more</a></p>
</div></div><h3 id='impl-Copy' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl<'a> <a class="trait" href="../../std/marker/trait.Copy.html" title="trait std::marker::Copy">Copy</a> for <a class="struct" href="../../std/fmt/struct.Arguments.html" title="struct std::fmt::Arguments">Arguments</a><'a></code><a href='#impl-Copy' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/fmt/mod.rs.html#425' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'></div></div>
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