<!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 `Result` type in crate `std`."> <meta name="keywords" content="rust, rustlang, rust-lang, Result"> <title>std::io::Result - 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="../../main.css" id="themeStyle"> <script src="../../storage.js"></script> <link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"> </head> <body class="rustdoc type"> <!--[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'>Type Definition Result</p><div class="sidebar-elems"><p class='location'><a href='../index.html'>std</a>::<wbr><a href='index.html'>io</a></p><script>window.sidebarCurrent = {name: 'Result', ty: 'type', 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"> </div> </form> </nav> <section id='main' class="content"> <h1 class='fqn'><span class='in-band'>Type Definition <a href='../index.html'>std</a>::<wbr><a href='index.html'>io</a>::<wbr><a class="type" href=''>Result</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/std/io/error.rs.html#52' title='goto source code'>[src]</a></span></h1> <pre class='rust typedef'>type Result<T> = <a class="enum" href="../../std/result/enum.Result.html" title="enum std::result::Result">Result</a><T, <a class="struct" href="../../std/io/struct.Error.html" title="struct std::io::Error">Error</a>>;</pre><div class='docblock'><p>A specialized <a href="../result/enum.Result.html"><code>Result</code></a> type for I/O operations.</p> <p>This type is broadly used across <a href="../io/index.html"><code>std::io</code></a> for any operation which may produce an error.</p> <p>This typedef is generally used to avoid writing out <a href="../io/struct.Error.html"><code>io::Error</code></a> directly and is otherwise a direct mapping to <a href="../result/enum.Result.html"><code>Result</code></a>.</p> <p>While usual Rust style is to import types directly, aliases of <a href="../result/enum.Result.html"><code>Result</code></a> often are not, to make it easier to distinguish between them. <a href="../result/enum.Result.html"><code>Result</code></a> is generally assumed to be <a href="../result/enum.Result.html"><code>std::result::Result</code></a>, and so users of this alias will generally use <code>io::Result</code> instead of shadowing the prelude's import of <a href="../result/enum.Result.html"><code>std::result::Result</code></a>.</p> <h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1> <p>A convenience function that bubbles an <code>io::Result</code> to its caller:</p> <pre class="rust rust-example-rendered"> <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>; <span class="kw">fn</span> <span class="ident">get_string</span>() <span class="op">-></span> <span class="ident">io</span>::<span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">String</span><span class="op">></span> { <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buffer</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">new</span>(); <span class="ident">io</span>::<span class="ident">stdin</span>().<span class="ident">read_line</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buffer</span>)<span class="question-mark">?</span>; <span class="prelude-val">Ok</span>(<span class="ident">buffer</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%3Aio%3B%0A%0Afn%20get_string()%20-%3E%20io%3A%3AResult%3CString%3E%20%7B%0A%20%20%20%20let%20mut%20buffer%20%3D%20String%3A%3Anew()%3B%0A%0A%20%20%20%20io%3A%3Astdin().read_line(%26mut%20buffer)%3F%3B%0A%0A%20%20%20%20Ok(buffer)%0A%7D%0A%7D">Run</a></pre> </div></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 results</dd> <dt><kbd>↓</kbd></dt> <dd>Move down in search results</dd> <dt><kbd>↹</kbd></dt> <dd>Switch tab</dd> <dt><kbd>⏎</kbd></dt> <dd>Go to active search result</dd> <dt><kbd>+</kbd></dt> <dd>Expand all sections</dd> <dt><kbd>-</kbd></dt> <dd>Collapse all sections</dd> </dl> </div> <div class="infos"> <h2>Search Tricks</h2> <p> Prefix searches with a type followed by a colon (e.g. <code>fn:</code>) to restrict the search to a given type. </p> <p> Accepted types are: <code>fn</code>, <code>mod</code>, <code>struct</code>, <code>enum</code>, <code>trait</code>, <code>type</code>, <code>macro</code>, and <code>const</code>. </p> <p> Search functions by type signature (e.g. <code>vec -> usize</code> or <code>* -> vec</code>) </p> </div> </div> </aside> <script> window.rootPath = "../../"; 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