<!DOCTYPE HTML> <html lang="en" class="sidebar-visible no-js"> <head> <!-- Book generated using mdBook --> <meta charset="UTF-8"> <title>B - Operators and Symbols - The Rust Programming Language</title> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> <meta name="description" content=""> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="theme-color" content="#ffffff" /> <base href=""> <link rel="stylesheet" href="book.css"> <link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css"> <link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css"> <link rel="shortcut icon" href="favicon.png"> <!-- Font Awesome --> <link rel="stylesheet" href="_FontAwesome/css/font-awesome.css"> <link rel="stylesheet" href="highlight.css"> <link rel="stylesheet" href="tomorrow-night.css"> <link rel="stylesheet" href="ayu-highlight.css"> <!-- Custom theme stylesheets --> </head> <body class="light"> <!-- Work around some values being stored in localStorage wrapped in quotes --> <script type="text/javascript"> try { var theme = localStorage.getItem('mdbook-theme'); var sidebar = localStorage.getItem('mdbook-sidebar'); if (theme.startsWith('"') && theme.endsWith('"')) { localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1)); } if (sidebar.startsWith('"') && sidebar.endsWith('"')) { localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1)); } } catch (e) { } </script> <!-- Set the theme before any content is loaded, prevents flash --> <script type="text/javascript"> var theme; try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { } if (theme === null || theme === undefined) { theme = 'light'; } document.body.className = theme; document.querySelector('html').className = theme + ' js'; </script> <!-- Hide / unhide sidebar before it is displayed --> <script type="text/javascript"> var html = document.querySelector('html'); var sidebar = 'hidden'; if (document.body.clientWidth >= 1080) { try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { } sidebar = sidebar || 'visible'; } html.classList.remove('sidebar-visible'); html.classList.add("sidebar-" + sidebar); </script> <nav id="sidebar" class="sidebar" aria-label="Table of contents"> <ol class="chapter"><li class="affix"><a href="foreword.html">Foreword</a></li><li class="affix"><a href="ch00-00-introduction.html">Introduction</a></li><li><a href="ch01-00-getting-started.html"><strong aria-hidden="true">1.</strong> Getting Started</a></li><li><ol class="section"><li><a href="ch01-01-installation.html"><strong aria-hidden="true">1.1.</strong> Installation</a></li><li><a href="ch01-02-hello-world.html"><strong aria-hidden="true">1.2.</strong> Hello, World!</a></li><li><a href="ch01-03-hello-cargo.html"><strong aria-hidden="true">1.3.</strong> Hello, Cargo!</a></li></ol></li><li><a href="ch02-00-guessing-game-tutorial.html"><strong aria-hidden="true">2.</strong> Programming a Guessing Game</a></li><li><a href="ch03-00-common-programming-concepts.html"><strong aria-hidden="true">3.</strong> Common Programming Concepts</a></li><li><ol class="section"><li><a href="ch03-01-variables-and-mutability.html"><strong aria-hidden="true">3.1.</strong> Variables and Mutability</a></li><li><a href="ch03-02-data-types.html"><strong aria-hidden="true">3.2.</strong> Data Types</a></li><li><a href="ch03-03-how-functions-work.html"><strong aria-hidden="true">3.3.</strong> How Functions Work</a></li><li><a href="ch03-04-comments.html"><strong aria-hidden="true">3.4.</strong> Comments</a></li><li><a href="ch03-05-control-flow.html"><strong aria-hidden="true">3.5.</strong> Control Flow</a></li></ol></li><li><a href="ch04-00-understanding-ownership.html"><strong aria-hidden="true">4.</strong> Understanding Ownership</a></li><li><ol class="section"><li><a href="ch04-01-what-is-ownership.html"><strong aria-hidden="true">4.1.</strong> What is Ownership?</a></li><li><a href="ch04-02-references-and-borrowing.html"><strong aria-hidden="true">4.2.</strong> References & Borrowing</a></li><li><a href="ch04-03-slices.html"><strong aria-hidden="true">4.3.</strong> Slices</a></li></ol></li><li><a href="ch05-00-structs.html"><strong aria-hidden="true">5.</strong> Using Structs to Structure Related Data</a></li><li><ol class="section"><li><a href="ch05-01-defining-structs.html"><strong aria-hidden="true">5.1.</strong> Defining and Instantiating Structs</a></li><li><a href="ch05-02-example-structs.html"><strong aria-hidden="true">5.2.</strong> An Example Program Using Structs</a></li><li><a href="ch05-03-method-syntax.html"><strong aria-hidden="true">5.3.</strong> Method Syntax</a></li></ol></li><li><a href="ch06-00-enums.html"><strong aria-hidden="true">6.</strong> Enums and Pattern Matching</a></li><li><ol class="section"><li><a href="ch06-01-defining-an-enum.html"><strong aria-hidden="true">6.1.</strong> Defining an Enum</a></li><li><a href="ch06-02-match.html"><strong aria-hidden="true">6.2.</strong> The match Control Flow Operator</a></li><li><a href="ch06-03-if-let.html"><strong aria-hidden="true">6.3.</strong> Concise Control Flow with if let</a></li></ol></li><li><a href="ch07-00-modules.html"><strong aria-hidden="true">7.</strong> Modules</a></li><li><ol class="section"><li><a href="ch07-01-mod-and-the-filesystem.html"><strong aria-hidden="true">7.1.</strong> mod and the Filesystem</a></li><li><a href="ch07-02-controlling-visibility-with-pub.html"><strong aria-hidden="true">7.2.</strong> Controlling Visibility with pub</a></li><li><a href="ch07-03-importing-names-with-use.html"><strong aria-hidden="true">7.3.</strong> Referring to Names in Different Modules</a></li></ol></li><li><a href="ch08-00-common-collections.html"><strong aria-hidden="true">8.</strong> Common Collections</a></li><li><ol class="section"><li><a href="ch08-01-vectors.html"><strong aria-hidden="true">8.1.</strong> Vectors</a></li><li><a href="ch08-02-strings.html"><strong aria-hidden="true">8.2.</strong> Strings</a></li><li><a href="ch08-03-hash-maps.html"><strong aria-hidden="true">8.3.</strong> Hash Maps</a></li></ol></li><li><a href="ch09-00-error-handling.html"><strong aria-hidden="true">9.</strong> Error Handling</a></li><li><ol class="section"><li><a href="ch09-01-unrecoverable-errors-with-panic.html"><strong aria-hidden="true">9.1.</strong> Unrecoverable Errors with panic!</a></li><li><a href="ch09-02-recoverable-errors-with-result.html"><strong aria-hidden="true">9.2.</strong> Recoverable Errors with Result</a></li><li><a href="ch09-03-to-panic-or-not-to-panic.html"><strong aria-hidden="true">9.3.</strong> To panic! or Not To panic!</a></li></ol></li><li><a href="ch10-00-generics.html"><strong aria-hidden="true">10.</strong> Generic Types, Traits, and Lifetimes</a></li><li><ol class="section"><li><a href="ch10-01-syntax.html"><strong aria-hidden="true">10.1.</strong> Generic Data Types</a></li><li><a href="ch10-02-traits.html"><strong aria-hidden="true">10.2.</strong> Traits: Defining Shared Behavior</a></li><li><a href="ch10-03-lifetime-syntax.html"><strong aria-hidden="true">10.3.</strong> Validating References with Lifetimes</a></li></ol></li><li><a href="ch11-00-testing.html"><strong aria-hidden="true">11.</strong> Testing</a></li><li><ol class="section"><li><a href="ch11-01-writing-tests.html"><strong aria-hidden="true">11.1.</strong> Writing tests</a></li><li><a href="ch11-02-running-tests.html"><strong aria-hidden="true">11.2.</strong> Running tests</a></li><li><a href="ch11-03-test-organization.html"><strong aria-hidden="true">11.3.</strong> Test Organization</a></li></ol></li><li><a href="ch12-00-an-io-project.html"><strong aria-hidden="true">12.</strong> An I/O Project: Building a Command Line Program</a></li><li><ol class="section"><li><a href="ch12-01-accepting-command-line-arguments.html"><strong aria-hidden="true">12.1.</strong> Accepting Command Line Arguments</a></li><li><a href="ch12-02-reading-a-file.html"><strong aria-hidden="true">12.2.</strong> Reading a File</a></li><li><a href="ch12-03-improving-error-handling-and-modularity.html"><strong aria-hidden="true">12.3.</strong> Refactoring to Improve Modularity and Error Handling</a></li><li><a href="ch12-04-testing-the-librarys-functionality.html"><strong aria-hidden="true">12.4.</strong> Developing the Library’s Functionality with Test Driven Development</a></li><li><a href="ch12-05-working-with-environment-variables.html"><strong aria-hidden="true">12.5.</strong> Working with Environment Variables</a></li><li><a href="ch12-06-writing-to-stderr-instead-of-stdout.html"><strong aria-hidden="true">12.6.</strong> Writing Error Messages to Standard Error Instead of Standard Output</a></li></ol></li><li><a href="ch13-00-functional-features.html"><strong aria-hidden="true">13.</strong> Functional Language Features: Iterators and Closures</a></li><li><ol class="section"><li><a href="ch13-01-closures.html"><strong aria-hidden="true">13.1.</strong> Closures: Anonymous Functions that Can Capture Their Environment</a></li><li><a href="ch13-02-iterators.html"><strong aria-hidden="true">13.2.</strong> Processing a Series of Items with Iterators</a></li><li><a href="ch13-03-improving-our-io-project.html"><strong aria-hidden="true">13.3.</strong> Improving Our I/O Project</a></li><li><a href="ch13-04-performance.html"><strong aria-hidden="true">13.4.</strong> Comparing Performance: Loops vs. Iterators</a></li></ol></li><li><a href="ch14-00-more-about-cargo.html"><strong aria-hidden="true">14.</strong> More about Cargo and Crates.io</a></li><li><ol class="section"><li><a href="ch14-01-release-profiles.html"><strong aria-hidden="true">14.1.</strong> Customizing Builds with Release Profiles</a></li><li><a href="ch14-02-publishing-to-crates-io.html"><strong aria-hidden="true">14.2.</strong> Publishing a Crate to Crates.io</a></li><li><a href="ch14-03-cargo-workspaces.html"><strong aria-hidden="true">14.3.</strong> Cargo Workspaces</a></li><li><a href="ch14-04-installing-binaries.html"><strong aria-hidden="true">14.4.</strong> Installing Binaries from Crates.io with cargo install</a></li><li><a href="ch14-05-extending-cargo.html"><strong aria-hidden="true">14.5.</strong> Extending Cargo with Custom Commands</a></li></ol></li><li><a href="ch15-00-smart-pointers.html"><strong aria-hidden="true">15.</strong> Smart Pointers</a></li><li><ol class="section"><li><a href="ch15-01-box.html"><strong aria-hidden="true">15.1.</strong> Box<T> Points to Data on the Heap and Has a Known Size</a></li><li><a href="ch15-02-deref.html"><strong aria-hidden="true">15.2.</strong> The Deref Trait Allows Access to the Data Through a Reference</a></li><li><a href="ch15-03-drop.html"><strong aria-hidden="true">15.3.</strong> The Drop Trait Runs Code on Cleanup</a></li><li><a href="ch15-04-rc.html"><strong aria-hidden="true">15.4.</strong> Rc<T>, the Reference Counted Smart Pointer</a></li><li><a href="ch15-05-interior-mutability.html"><strong aria-hidden="true">15.5.</strong> RefCell<T> and the Interior Mutability Pattern</a></li><li><a href="ch15-06-reference-cycles.html"><strong aria-hidden="true">15.6.</strong> Creating Reference Cycles and Leaking Memory is Safe</a></li></ol></li><li><a href="ch16-00-concurrency.html"><strong aria-hidden="true">16.</strong> Fearless Concurrency</a></li><li><ol class="section"><li><a href="ch16-01-threads.html"><strong aria-hidden="true">16.1.</strong> Threads</a></li><li><a href="ch16-02-message-passing.html"><strong aria-hidden="true">16.2.</strong> Message Passing</a></li><li><a href="ch16-03-shared-state.html"><strong aria-hidden="true">16.3.</strong> Shared State</a></li><li><a href="ch16-04-extensible-concurrency-sync-and-send.html"><strong aria-hidden="true">16.4.</strong> Extensible Concurrency: Sync and Send</a></li></ol></li><li><a href="ch17-00-oop.html"><strong aria-hidden="true">17.</strong> Object Oriented Programming Features of Rust</a></li><li><ol class="section"><li><a href="ch17-01-what-is-oo.html"><strong aria-hidden="true">17.1.</strong> Characteristics of Object-Oriented Languages</a></li><li><a href="ch17-02-trait-objects.html"><strong aria-hidden="true">17.2.</strong> Using Trait Objects that Allow for Values of Different Types</a></li><li><a href="ch17-03-oo-design-patterns.html"><strong aria-hidden="true">17.3.</strong> Implementing an Object-Oriented Design Pattern</a></li></ol></li><li><a href="ch18-00-patterns.html"><strong aria-hidden="true">18.</strong> Patterns Match the Structure of Values</a></li><li><ol class="section"><li><a href="ch18-01-all-the-places-for-patterns.html"><strong aria-hidden="true">18.1.</strong> All the Places Patterns May be Used</a></li><li><a href="ch18-02-refutability.html"><strong aria-hidden="true">18.2.</strong> Refutability: Whether a Pattern Might Fail to Match</a></li><li><a href="ch18-03-pattern-syntax.html"><strong aria-hidden="true">18.3.</strong> All the Pattern Syntax</a></li></ol></li><li><a href="ch19-00-advanced-features.html"><strong aria-hidden="true">19.</strong> Advanced Features</a></li><li><ol class="section"><li><a href="ch19-01-unsafe-rust.html"><strong aria-hidden="true">19.1.</strong> Unsafe Rust</a></li><li><a href="ch19-02-advanced-lifetimes.html"><strong aria-hidden="true">19.2.</strong> Advanced Lifetimes</a></li><li><a href="ch19-03-advanced-traits.html"><strong aria-hidden="true">19.3.</strong> Advanced Traits</a></li><li><a href="ch19-04-advanced-types.html"><strong aria-hidden="true">19.4.</strong> Advanced Types</a></li><li><a href="ch19-05-advanced-functions-and-closures.html"><strong aria-hidden="true">19.5.</strong> Advanced Functions & Closures</a></li></ol></li><li><a href="ch20-00-final-project-a-web-server.html"><strong aria-hidden="true">20.</strong> Final Project: Building a Multithreaded Web Server</a></li><li><ol class="section"><li><a href="ch20-01-single-threaded.html"><strong aria-hidden="true">20.1.</strong> A Single Threaded Web Server</a></li><li><a href="ch20-02-multithreaded.html"><strong aria-hidden="true">20.2.</strong> Turning our Single Threaded Server into a Multithreaded Server</a></li><li><a href="ch20-03-graceful-shutdown-and-cleanup.html"><strong aria-hidden="true">20.3.</strong> Graceful Shutdown and Cleanup</a></li></ol></li><li><a href="appendix-00.html"><strong aria-hidden="true">21.</strong> Appendix</a></li><li><ol class="section"><li><a href="appendix-01-keywords.html"><strong aria-hidden="true">21.1.</strong> A - Keywords</a></li><li><a href="appendix-02-operators.html" class="active"><strong aria-hidden="true">21.2.</strong> B - Operators and Symbols</a></li><li><a href="appendix-03-derivable-traits.html"><strong aria-hidden="true">21.3.</strong> C - Derivable Traits</a></li><li><a href="appendix-04-macros.html"><strong aria-hidden="true">21.4.</strong> D - Macros</a></li><li><a href="appendix-05-translation.html"><strong aria-hidden="true">21.5.</strong> E - Translations</a></li><li><a href="appendix-06-newest-features.html"><strong aria-hidden="true">21.6.</strong> F - Newest Features</a></li><li><a href="appendix-07-nightly-rust.html"><strong aria-hidden="true">21.7.</strong> G - How Rust is Made and “Nightly Rust”</a></li></ol></li></ol> </nav> <div id="page-wrapper" class="page-wrapper"> <div class="page"> <div id="menu-bar" class="menu-bar"> <div id="menu-bar-sticky-container"> <div class="left-buttons"> <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar"> <i class="fa fa-bars"></i> </button> <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list"> <i class="fa fa-paint-brush"></i> </button> <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu"> <li role="none"><button role="menuitem" class="theme" id="light">Light <span class="default">(default)</span></button></li> <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li> <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li> <li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li> <li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li> </ul> <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar"> <i class="fa fa-search"></i> </button> </div> <h1 class="menu-title">The Rust Programming Language</h1> <div class="right-buttons"> <a href="print.html" title="Print this book" aria-label="Print this book"> <i id="print-button" class="fa fa-print"></i> </a> </div> </div> </div> <div id="search-wrapper" class="hidden"> <form id="searchbar-outer" class="searchbar-outer"> <input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header"> </form> <div id="searchresults-outer" class="searchresults-outer hidden"> <div id="searchresults-header" class="searchresults-header"></div> <ul id="searchresults"> </ul> </div> </div> <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM --> <script type="text/javascript"> document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible'); document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible'); Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) { link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1); }); </script> <div id="content" class="content"> <main> <a class="header" href="appendix-02-operators.html#appendix-b-operators-and-symbols" id="appendix-b-operators-and-symbols"><h2>Appendix B: Operators and Symbols</h2></a> <p>This appendix contains a glossary of Rust’s syntax, including operators and other symbols that appear by themselves or in the context of paths, generics, trait bounds, macros, attributes, comments, tuples, and brackets.</p> <a class="header" href="appendix-02-operators.html#operators" id="operators"><h3>Operators</h3></a> <p>The following list contains the operators in Rust, an example of how the operator would appear in context, a short explanation, and whether that operator is overloadable. If an operator is overloadable, the relevant trait to use to overload that operator is listed.</p> <ul> <li><code>!</code> (<code>ident!(...)</code>, <code>ident!{...}</code>, <code>ident![...]</code>): denotes macro expansion.</li> <li><code>!</code> (<code>!expr</code>): bitwise or logical complement. Overloadable (<code>Not</code>).</li> <li><code>!=</code> (<code>var != expr</code>): nonequality comparison. Overloadable (<code>PartialEq</code>).</li> <li><code>%</code> (<code>expr % expr</code>): arithmetic remainder. Overloadable (<code>Rem</code>).</li> <li><code>%=</code> (<code>var %= expr</code>): arithmetic remainder and assignment. Overloadable (<code>RemAssign</code>).</li> <li><code>&</code> (<code>&expr</code>, <code>&mut expr</code>): borrow.</li> <li><code>&</code> (<code>&type</code>, <code>&mut type</code>, <code>&'a type</code>, <code>&'a mut type</code>): borrowed pointer type.</li> <li><code>&</code> (<code>expr & expr</code>): bitwise AND. Overloadable (<code>BitAnd</code>).</li> <li><code>&=</code> (<code>var &= expr</code>): bitwise AND and assignment. Overloadable (<code>BitAndAssign</code>).</li> <li><code>&&</code> (<code>expr && expr</code>): logical AND.</li> <li><code>*</code> (<code>expr * expr</code>): arithmetic multiplication. Overloadable (<code>Mul</code>).</li> <li><code>*</code> (<code>*expr</code>): dereference.</li> <li><code>*</code> (<code>*const type</code>, <code>*mut type</code>): raw pointer.</li> <li><code>*=</code> (<code>var *= expr</code>): arithmetic multiplication and assignment. Overloadable (<code>MulAssign</code>).</li> <li><code>+</code> (<code>trait + trait</code>, <code>'a + trait</code>): compound type constraint.</li> <li><code>+</code> (<code>expr + expr</code>): arithmetic addition. Overloadable (<code>Add</code>).</li> <li><code>+=</code> (<code>var += expr</code>): arithmetic addition and assignment. Overloadable (<code>AddAssign</code>).</li> <li><code>,</code>: argument and element separator.</li> <li><code>-</code> (<code>- expr</code>): arithmetic negation. Overloadable (<code>Neg</code>).</li> <li><code>-</code> (<code>expr - expr</code>): arithmetic subtraction. Overloadable (<code>Sub</code>).</li> <li><code>-=</code> (<code>var -= expr</code>): arithmetic subtraction and assignment. Overloadable (<code>SubAssign</code>).</li> <li><code>-></code> (<code>fn(...) -> type</code>, <code>|...| -> type</code>): function and closure return type.</li> <li><code>.</code> (<code>expr.ident</code>): member access.</li> <li><code>..</code> (<code>..</code>, <code>expr..</code>, <code>..expr</code>, <code>expr..expr</code>): right-exclusive range literal.</li> <li><code>..</code> (<code>..expr</code>): struct literal update syntax.</li> <li><code>..</code> (<code>variant(x, ..)</code>, <code>struct_type { x, .. }</code>): “and the rest” pattern binding.</li> <li><code>...</code> (<code>expr...expr</code>) <em>in a pattern</em>: inclusive range pattern.</li> <li><code>/</code> (<code>expr / expr</code>): arithmetic division. Overloadable (<code>Div</code>).</li> <li><code>/=</code> (<code>var /= expr</code>): arithmetic division and assignment. Overloadable (<code>DivAssign</code>).</li> <li><code>:</code> (<code>pat: type</code>, <code>ident: type</code>): constraints.</li> <li><code>:</code> (<code>ident: expr</code>): struct field initializer.</li> <li><code>:</code> (<code>'a: loop {...}</code>): loop label.</li> <li><code>;</code>: statement and item terminator.</li> <li><code>;</code> (<code>[...; len]</code>): part of fixed-size array syntax</li> <li><code><<</code> (<code>expr << expr</code>): left-shift. Overloadable (<code>Shl</code>).</li> <li><code><<=</code> (<code>var <<= expr</code>): left-shift and assignment. Overloadable (<code>ShlAssign</code>).</li> <li><code><</code> (<code>expr < expr</code>): less-than comparison. Overloadable (<code>PartialOrd</code>).</li> <li><code><=</code> (<code>expr <= expr</code>): less-than or equal-to comparison. Overloadable (<code>PartialOrd</code>).</li> <li><code>=</code> (<code>var = expr</code>, <code>ident = type</code>): assignment/equivalence.</li> <li><code>==</code> (<code>expr == expr</code>): equality comparison. Overloadable (<code>PartialEq</code>).</li> <li><code>=></code> (<code>pat => expr</code>): part of match arm syntax.</li> <li><code>></code> (<code>expr > expr</code>): greater-than comparison. Overloadable (<code>PartialOrd</code>).</li> <li><code>>=</code> (<code>expr >= expr</code>): greater-than or equal-to comparison. Overloadable (<code>PartialOrd</code>).</li> <li><code>>></code> (<code>expr >> expr</code>): right-shift. Overloadable (<code>Shr</code>).</li> <li><code>>>=</code> (<code>var >>= expr</code>): right-shift and assignment. Overloadable (<code>ShrAssign</code>).</li> <li><code>@</code> (<code>ident @ pat</code>): pattern binding.</li> <li><code>^</code> (<code>expr ^ expr</code>): bitwise exclusive OR. Overloadable (<code>BitXor</code>).</li> <li><code>^=</code> (<code>var ^= expr</code>): bitwise exclusive OR and assignment. Overloadable (<code>BitXorAssign</code>).</li> <li><code>|</code> (<code>pat | pat</code>): pattern alternatives.</li> <li><code>|</code> (<code>|…| expr</code>): closures.</li> <li><code>|</code> (<code>expr | expr</code>): bitwise OR. Overloadable (<code>BitOr</code>).</li> <li><code>|=</code> (<code>var |= expr</code>): bitwise OR and assignment. Overloadable (<code>BitOrAssign</code>).</li> <li><code>||</code> (<code>expr || expr</code>): logical OR.</li> <li><code>_</code>: “ignored” pattern binding. Also used to make integer literals readable.</li> <li><code>?</code> (<code>expr?</code>): error propagation.</li> </ul> <a class="header" href="appendix-02-operators.html#non-operator-symbols" id="non-operator-symbols"><h3>Non-operator Symbols</h3></a> <p>The following list contains all non-letters that don’t function as operators; that is, they don’t behave like a function or method call.</p> <a class="header" href="appendix-02-operators.html#stand-alone-syntax" id="stand-alone-syntax"><h4>Stand-Alone Syntax</h4></a> <ul> <li><code>'ident</code>: named lifetime or loop label.</li> <li><code>...u8</code>, <code>...i32</code>, <code>...f64</code>, <code>...usize</code>, <em>etc.</em>: numeric literal of specific type.</li> <li><code>"..."</code>: string literal.</li> <li><code>r"..."</code>, <code>r#"..."#</code>, <code>r##"..."##</code>, <em>etc.</em>: raw string literal, escape characters are not processed.</li> <li><code>b"..."</code>: byte string literal, constructs a <code>[u8]</code> instead of a string.</li> <li><code>br"..."</code>, <code>br#"..."#</code>, <code>br##"..."##</code>, <em>etc.</em>: raw byte string literal, combination of raw and byte string literal.</li> <li><code>'...'</code>: character literal.</li> <li><code>b'...'</code>: ASCII byte literal.</li> <li><code>|...| expr</code>: closure.</li> <li><code>!</code>: always empty bottom type for diverging functions.</li> </ul> <a class="header" href="appendix-02-operators.html#path-related-syntax" id="path-related-syntax"><h4>Path-Related Syntax</h4></a> <ul> <li><code>ident::ident</code>: namespace path.</li> <li><code>::path</code>: path relative to the crate root (<em>i.e.</em>, an explicitly absolute path).</li> <li><code>self::path</code>: path relative to the current module (<em>i.e.</em>, an explicitly relative path).</li> <li><code>super::path</code>: path relative to the parent of the current module.</li> <li><code>type::ident</code>, <code><type as trait>::ident</code>: associated constants, functions, and types.</li> <li><code><type>::...</code>: associated item for a type that cannot be directly named (<em>e.g.</em>, <code><&T>::...</code>, <code><[T]>::...</code>, <em>etc.</em>).</li> <li><code>trait::method(...)</code>: disambiguating a method call by naming the trait that defines it.</li> <li><code>type::method(...)</code>: disambiguating a method call by naming the type for which it’s defined.</li> <li><code><type as trait>::method(...)</code>: disambiguating a method call by naming the trait <em>and</em> type.</li> </ul> <a class="header" href="appendix-02-operators.html#generics" id="generics"><h4>Generics</h4></a> <ul> <li><code>path<...></code> (<em>e.g.</em>, <code>Vec<u8></code>): specifies parameters to generic type <em>in a type</em>.</li> <li><code>path::<...></code>, <code>method::<...></code> (<em>e.g.</em>, <code>"42".parse::<i32>()</code>): specifies parameters to generic type, function, or method <em>in an expression</em>. Often referred to as <em>turbofish</em>.</li> <li><code>fn ident<...> ...</code>: define generic function.</li> <li><code>struct ident<...> ...</code>: define generic structure.</li> <li><code>enum ident<...> ...</code>: define generic enumeration.</li> <li><code>impl<...> ...</code>: define generic implementation.</li> <li><code>for<...> type</code>: higher-ranked lifetime bounds.</li> <li><code>type<ident=type></code> (<em>e.g.</em>, <code>Iterator<Item=T></code>): a generic type where one or more associated types have specific assignments.</li> </ul> <a class="header" href="appendix-02-operators.html#trait-bound-constraints" id="trait-bound-constraints"><h4>Trait Bound Constraints</h4></a> <ul> <li><code>T: U</code>: generic parameter <code>T</code> constrained to types that implement <code>U</code>.</li> <li><code>T: 'a</code>: generic type <code>T</code> must outlive lifetime <code>'a</code>. When we say that a type “outlives” the lifetime, we mean it cannot transitively contain any references with lifetimes shorter than <code>'a</code>.</li> <li><code>T : 'static</code>: the generic type <code>T</code> contains no borrowed references other than <code>'static</code> ones.</li> <li><code>'b: 'a</code>: generic lifetime <code>'b</code> must outlive lifetime <code>'a</code>.</li> <li><code>T: ?Sized</code>: allow generic type parameter to be a dynamically sized type.</li> <li><code>'a + trait</code>, <code>trait + trait</code>: compound type constraint.</li> </ul> <a class="header" href="appendix-02-operators.html#macros-and-attributes" id="macros-and-attributes"><h4>Macros and Attributes</h4></a> <ul> <li><code>#[meta]</code>: outer attribute.</li> <li><code>#![meta]</code>: inner attribute.</li> <li><code>$ident</code>: macro substitution.</li> <li><code>$ident:kind</code>: macro capture.</li> <li><code>$(…)…</code>: macro repetition.</li> </ul> <a class="header" href="appendix-02-operators.html#comments" id="comments"><h4>Comments</h4></a> <ul> <li><code>//</code>: line comment.</li> <li><code>//!</code>: inner line doc comment.</li> <li><code>///</code>: outer line doc comment.</li> <li><code>/*...*/</code>: block comment.</li> <li><code>/*!...*/</code>: inner block doc comment.</li> <li><code>/**...*/</code>: outer block doc comment.</li> </ul> <a class="header" href="appendix-02-operators.html#tuples" id="tuples"><h4>Tuples</h4></a> <ul> <li><code>()</code>: empty tuple (<em>aka</em> unit), both literal and type.</li> <li><code>(expr)</code>: parenthesized expression.</li> <li><code>(expr,)</code>: single-element tuple expression.</li> <li><code>(type,)</code>: single-element tuple type.</li> <li><code>(expr, ...)</code>: tuple expression.</li> <li><code>(type, ...)</code>: tuple type.</li> <li><code>expr(expr, ...)</code>: function call expression. Also used to initialize tuple <code>struct</code>s and tuple <code>enum</code> variants.</li> <li><code>ident!(...)</code>, <code>ident!{...}</code>, <code>ident![...]</code>: macro invocation.</li> <li><code>expr.0</code>, <code>expr.1</code>, <em>etc.</em>: tuple indexing.</li> </ul> <a class="header" href="appendix-02-operators.html#curly-brackets" id="curly-brackets"><h4>Curly Brackets</h4></a> <ul> <li><code>{...}</code>: block expression.</li> <li><code>Type {...}</code>: <code>struct</code> literal.</li> </ul> <a class="header" href="appendix-02-operators.html#square-brackets" id="square-brackets"><h4>Square Brackets</h4></a> <ul> <li><code>[...]</code>: array literal.</li> <li><code>[expr; len]</code>: array literal containing <code>len</code> copies of <code>expr</code>.</li> <li><code>[type; len]</code>: array type containing <code>len</code> instances of <code>type</code>.</li> <li><code>expr[expr]</code>: collection indexing. Overloadable (<code>Index</code>, <code>IndexMut</code>).</li> <li><code>expr[..]</code>, <code>expr[a..]</code>, <code>expr[..b]</code>, <code>expr[a..b]</code>: collection indexing pretending to be collection slicing, using <code>Range</code>, <code>RangeFrom</code>, <code>RangeTo</code>, or <code>RangeFull</code> as the “index.”</li> </ul> </main> <nav class="nav-wrapper" aria-label="Page navigation"> <!-- Mobile navigation buttons --> <a rel="prev" href="appendix-01-keywords.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next" href="appendix-03-derivable-traits.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> <div style="clear: both"></div> </nav> </div> </div> <nav class="nav-wide-wrapper" aria-label="Page navigation"> <a href="appendix-01-keywords.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a href="appendix-03-derivable-traits.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> </nav> </div> <script src="searchindex.js" type="text/javascript" charset="utf-8"></script> <script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script> <script src="mark.min.js" type="text/javascript" charset="utf-8"></script> <script src="searcher.js" type="text/javascript" charset="utf-8"></script> <script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script> <script src="highlight.js" type="text/javascript" charset="utf-8"></script> <script src="book.js" type="text/javascript" charset="utf-8"></script> <!-- Custom JS scripts --> </body> </html>