<!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 `from_digit` fn in crate `std`."> <meta name="keywords" content="rust, rustlang, rust-lang, from_digit"> <title>std::char::from_digit - 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 fn"> <!--[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'><a href='../index.html'>std</a>::<wbr><a href='index.html'>char</a></p><script>window.sidebarCurrent = {name: 'from_digit', ty: 'fn', relpath: ''};</script><script defer src="sidebar-items.js"></script> </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'>Function <a href='../index.html'>std</a>::<wbr><a href='index.html'>char</a>::<wbr><a class="fn" href=''>from_digit</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/char.rs.html#350-364' title='goto source code'>[src]</a></span></h1> <pre class='rust fn'>pub fn from_digit(num: <a class="primitive" href="../primitive.u32.html">u32</a>, radix: <a class="primitive" href="../primitive.u32.html">u32</a>) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.char.html">char</a>></pre><div class='docblock'><p>Converts a digit in the given radix to a <code>char</code>.</p> <p>A 'radix' here is sometimes also called a 'base'. A radix of two indicates a binary number, a radix of ten, decimal, and a radix of sixteen, hexadecimal, to give some common values. Arbitrary radices are supported.</p> <p><code>from_digit()</code> will return <code>None</code> if the input is not a digit in the given radix.</p> <h1 id="panics" class="section-header"><a href="#panics">Panics</a></h1> <p>Panics if given a radix larger than 36.</p> <h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1> <p>Basic usage:</p> <pre class="rust rust-example-rendered"> <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">char</span>; <span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="ident">char</span>::<span class="ident">from_digit</span>(<span class="number">4</span>, <span class="number">10</span>); <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Some</span>(<span class="string">'4'</span>), <span class="ident">c</span>); <span class="comment">// Decimal 11 is a single digit in base 16</span> <span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="ident">char</span>::<span class="ident">from_digit</span>(<span class="number">11</span>, <span class="number">16</span>); <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Some</span>(<span class="string">'b'</span>), <span class="ident">c</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%3Achar%3B%0A%0Alet%20c%20%3D%20char%3A%3Afrom_digit(4%2C%2010)%3B%0A%0Aassert_eq!(Some('4')%2C%20c)%3B%0A%0A%2F%2F%20Decimal%2011%20is%20a%20single%20digit%20in%20base%2016%0Alet%20c%20%3D%20char%3A%3Afrom_digit(11%2C%2016)%3B%0A%0Aassert_eq!(Some('b')%2C%20c)%3B%0A%7D">Run</a></pre> <p>Returning <code>None</code> when the input is not a digit:</p> <pre class="rust rust-example-rendered"> <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">char</span>; <span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="ident">char</span>::<span class="ident">from_digit</span>(<span class="number">20</span>, <span class="number">10</span>); <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">None</span>, <span class="ident">c</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%3Achar%3B%0A%0Alet%20c%20%3D%20char%3A%3Afrom_digit(20%2C%2010)%3B%0A%0Aassert_eq!(None%2C%20c)%3B%0A%7D">Run</a></pre> <p>Passing a large radix, causing a panic:</p> <pre class="rust rust-example-rendered"> <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">thread</span>; <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">char</span>; <span class="kw">let</span> <span class="ident">result</span> <span class="op">=</span> <span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="op">||</span> { <span class="comment">// this panics</span> <span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="ident">char</span>::<span class="ident">from_digit</span>(<span class="number">1</span>, <span class="number">37</span>); }).<span class="ident">join</span>(); <span class="macro">assert</span><span class="macro">!</span>(<span class="ident">result</span>.<span class="ident">is_err</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%3Athread%3B%0Ause%20std%3A%3Achar%3B%0A%0Alet%20result%20%3D%20thread%3A%3Aspawn(%7C%7C%20%7B%0A%20%20%20%20%2F%2F%20this%20panics%0A%20%20%20%20let%20c%20%3D%20char%3A%3Afrom_digit(1%2C%2037)%3B%0A%7D).join()%3B%0A%0Aassert!(result.is_err())%3B%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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