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<ol class="chapter"><li class="expanded affix "><a href="title-page.html">The Rust Programming Language</a></li><li class="expanded affix "><a href="foreword.html">Foreword</a></li><li class="expanded affix "><a href="ch00-00-introduction.html">Introduction</a></li><li class="expanded "><a href="ch01-00-getting-started.html"><strong aria-hidden="true">1.</strong> Getting Started</a></li><li><ol class="section"><li class="expanded "><a href="ch01-01-installation.html"><strong aria-hidden="true">1.1.</strong> Installation</a></li><li class="expanded "><a href="ch01-02-hello-world.html"><strong aria-hidden="true">1.2.</strong> Hello, World!</a></li><li class="expanded "><a href="ch01-03-hello-cargo.html"><strong aria-hidden="true">1.3.</strong> Hello, Cargo!</a></li></ol></li><li class="expanded "><a href="ch02-00-guessing-game-tutorial.html"><strong aria-hidden="true">2.</strong> Programming a Guessing Game</a></li><li class="expanded "><a href="ch03-00-common-programming-concepts.html"><strong aria-hidden="true">3.</strong> Common Programming Concepts</a></li><li><ol class="section"><li class="expanded "><a href="ch03-01-variables-and-mutability.html"><strong aria-hidden="true">3.1.</strong> Variables and Mutability</a></li><li class="expanded "><a href="ch03-02-data-types.html"><strong aria-hidden="true">3.2.</strong> Data Types</a></li><li class="expanded "><a href="ch03-03-how-functions-work.html"><strong aria-hidden="true">3.3.</strong> Functions</a></li><li class="expanded "><a href="ch03-04-comments.html"><strong aria-hidden="true">3.4.</strong> Comments</a></li><li class="expanded "><a href="ch03-05-control-flow.html"><strong aria-hidden="true">3.5.</strong> Control Flow</a></li></ol></li><li class="expanded "><a href="ch04-00-understanding-ownership.html"><strong aria-hidden="true">4.</strong> Understanding Ownership</a></li><li><ol class="section"><li class="expanded "><a href="ch04-01-what-is-ownership.html"><strong aria-hidden="true">4.1.</strong> What is Ownership?</a></li><li class="expanded "><a href="ch04-02-references-and-borrowing.html"><strong aria-hidden="true">4.2.</strong> References and Borrowing</a></li><li class="expanded "><a href="ch04-03-slices.html"><strong aria-hidden="true">4.3.</strong> The Slice Type</a></li></ol></li><li class="expanded "><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 class="expanded "><a href="ch05-01-defining-structs.html"><strong aria-hidden="true">5.1.</strong> Defining and Instantiating Structs</a></li><li class="expanded "><a href="ch05-02-example-structs.html"><strong aria-hidden="true">5.2.</strong> An Example Program Using Structs</a></li><li class="expanded "><a href="ch05-03-method-syntax.html"><strong aria-hidden="true">5.3.</strong> Method Syntax</a></li></ol></li><li class="expanded "><a href="ch06-00-enums.html"><strong aria-hidden="true">6.</strong> Enums and Pattern Matching</a></li><li><ol class="section"><li class="expanded "><a href="ch06-01-defining-an-enum.html"><strong aria-hidden="true">6.1.</strong> Defining an Enum</a></li><li class="expanded "><a href="ch06-02-match.html"><strong aria-hidden="true">6.2.</strong> The match Control Flow Operator</a></li><li class="expanded "><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 class="expanded "><a href="ch07-00-managing-growing-projects-with-packages-crates-and-modules.html"><strong aria-hidden="true">7.</strong> Managing Growing Projects with Packages, Crates, and Modules</a></li><li><ol class="section"><li class="expanded "><a href="ch07-01-packages-and-crates.html"><strong aria-hidden="true">7.1.</strong> Packages and Crates</a></li><li class="expanded "><a href="ch07-02-defining-modules-to-control-scope-and-privacy.html"><strong aria-hidden="true">7.2.</strong> Defining Modules to Control Scope and Privacy</a></li><li class="expanded "><a href="ch07-03-paths-for-referring-to-an-item-in-the-module-tree.html"><strong aria-hidden="true">7.3.</strong> Paths for Referring to an Item in the Module Tree</a></li><li class="expanded "><a href="ch07-04-bringing-paths-into-scope-with-the-use-keyword.html"><strong aria-hidden="true">7.4.</strong> Bringing Paths Into Scope with the use Keyword</a></li><li class="expanded "><a href="ch07-05-separating-modules-into-different-files.html"><strong aria-hidden="true">7.5.</strong> Separating Modules into Different Files</a></li></ol></li><li class="expanded "><a href="ch08-00-common-collections.html"><strong aria-hidden="true">8.</strong> Common Collections</a></li><li><ol class="section"><li class="expanded "><a href="ch08-01-vectors.html"><strong aria-hidden="true">8.1.</strong> Storing Lists of Values with Vectors</a></li><li class="expanded "><a href="ch08-02-strings.html"><strong aria-hidden="true">8.2.</strong> Storing UTF-8 Encoded Text with Strings</a></li><li class="expanded "><a href="ch08-03-hash-maps.html"><strong aria-hidden="true">8.3.</strong> Storing Keys with Associated Values in Hash Maps</a></li></ol></li><li class="expanded "><a href="ch09-00-error-handling.html"><strong aria-hidden="true">9.</strong> Error Handling</a></li><li><ol class="section"><li class="expanded "><a href="ch09-01-unrecoverable-errors-with-panic.html"><strong aria-hidden="true">9.1.</strong> Unrecoverable Errors with panic!</a></li><li class="expanded "><a href="ch09-02-recoverable-errors-with-result.html"><strong aria-hidden="true">9.2.</strong> Recoverable Errors with Result</a></li><li class="expanded "><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 class="expanded "><a href="ch10-00-generics.html"><strong aria-hidden="true">10.</strong> Generic Types, Traits, and Lifetimes</a></li><li><ol class="section"><li class="expanded "><a href="ch10-01-syntax.html"><strong aria-hidden="true">10.1.</strong> Generic Data Types</a></li><li class="expanded "><a href="ch10-02-traits.html"><strong aria-hidden="true">10.2.</strong> Traits: Defining Shared Behavior</a></li><li class="expanded "><a href="ch10-03-lifetime-syntax.html"><strong aria-hidden="true">10.3.</strong> Validating References with Lifetimes</a></li></ol></li><li class="expanded "><a href="ch11-00-testing.html"><strong aria-hidden="true">11.</strong> Writing Automated Tests</a></li><li><ol class="section"><li class="expanded "><a href="ch11-01-writing-tests.html"><strong aria-hidden="true">11.1.</strong> How to Write Tests</a></li><li class="expanded "><a href="ch11-02-running-tests.html"><strong aria-hidden="true">11.2.</strong> Controlling How Tests Are Run</a></li><li class="expanded "><a href="ch11-03-test-organization.html"><strong aria-hidden="true">11.3.</strong> Test Organization</a></li></ol></li><li class="expanded "><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 class="expanded "><a href="ch12-01-accepting-command-line-arguments.html"><strong aria-hidden="true">12.1.</strong> Accepting Command Line Arguments</a></li><li class="expanded "><a href="ch12-02-reading-a-file.html"><strong aria-hidden="true">12.2.</strong> Reading a File</a></li><li class="expanded "><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 class="expanded "><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 class="expanded "><a href="ch12-05-working-with-environment-variables.html"><strong aria-hidden="true">12.5.</strong> Working with Environment Variables</a></li><li class="expanded "><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 class="expanded "><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 class="expanded "><a href="ch13-01-closures.html"><strong aria-hidden="true">13.1.</strong> Closures: Anonymous Functions that Can Capture Their Environment</a></li><li class="expanded "><a href="ch13-02-iterators.html"><strong aria-hidden="true">13.2.</strong> Processing a Series of Items with Iterators</a></li><li class="expanded "><a href="ch13-03-improving-our-io-project.html"><strong aria-hidden="true">13.3.</strong> Improving Our I/O Project</a></li><li class="expanded "><a href="ch13-04-performance.html"><strong aria-hidden="true">13.4.</strong> Comparing Performance: Loops vs. Iterators</a></li></ol></li><li class="expanded "><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 class="expanded "><a href="ch14-01-release-profiles.html"><strong aria-hidden="true">14.1.</strong> Customizing Builds with Release Profiles</a></li><li class="expanded "><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 class="expanded "><a href="ch14-03-cargo-workspaces.html"><strong aria-hidden="true">14.3.</strong> Cargo Workspaces</a></li><li class="expanded "><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 class="expanded "><a href="ch14-05-extending-cargo.html"><strong aria-hidden="true">14.5.</strong> Extending Cargo with Custom Commands</a></li></ol></li><li class="expanded "><a href="ch15-00-smart-pointers.html"><strong aria-hidden="true">15.</strong> Smart Pointers</a></li><li><ol class="section"><li class="expanded "><a href="ch15-01-box.html"><strong aria-hidden="true">15.1.</strong> Using Box<T> to Point to Data on the Heap</a></li><li class="expanded "><a href="ch15-02-deref.html"><strong aria-hidden="true">15.2.</strong> Treating Smart Pointers Like Regular References with the Deref Trait</a></li><li class="expanded "><a href="ch15-03-drop.html"><strong aria-hidden="true">15.3.</strong> Running Code on Cleanup with the Drop Trait</a></li><li class="expanded "><a href="ch15-04-rc.html"><strong aria-hidden="true">15.4.</strong> Rc<T>, the Reference Counted Smart Pointer</a></li><li class="expanded "><a href="ch15-05-interior-mutability.html"><strong aria-hidden="true">15.5.</strong> RefCell<T> and the Interior Mutability Pattern</a></li><li class="expanded "><a href="ch15-06-reference-cycles.html"><strong aria-hidden="true">15.6.</strong> Reference Cycles Can Leak Memory</a></li></ol></li><li class="expanded "><a href="ch16-00-concurrency.html"><strong aria-hidden="true">16.</strong> Fearless Concurrency</a></li><li><ol class="section"><li class="expanded "><a href="ch16-01-threads.html"><strong aria-hidden="true">16.1.</strong> Using Threads to Run Code Simultaneously</a></li><li class="expanded "><a href="ch16-02-message-passing.html"><strong aria-hidden="true">16.2.</strong> Using Message Passing to Transfer Data Between Threads</a></li><li class="expanded "><a href="ch16-03-shared-state.html"><strong aria-hidden="true">16.3.</strong> Shared-State Concurrency</a></li><li class="expanded "><a href="ch16-04-extensible-concurrency-sync-and-send.html"><strong aria-hidden="true">16.4.</strong> Extensible Concurrency with the Sync and Send Traits</a></li></ol></li><li class="expanded "><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 class="expanded "><a href="ch17-01-what-is-oo.html"><strong aria-hidden="true">17.1.</strong> Characteristics of Object-Oriented Languages</a></li><li class="expanded "><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 class="expanded "><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 class="expanded "><a href="ch18-00-patterns.html"><strong aria-hidden="true">18.</strong> Patterns and Matching</a></li><li><ol class="section"><li class="expanded "><a href="ch18-01-all-the-places-for-patterns.html"><strong aria-hidden="true">18.1.</strong> All the Places Patterns Can Be Used</a></li><li class="expanded "><a href="ch18-02-refutability.html"><strong aria-hidden="true">18.2.</strong> Refutability: Whether a Pattern Might Fail to Match</a></li><li class="expanded "><a href="ch18-03-pattern-syntax.html"><strong aria-hidden="true">18.3.</strong> Pattern Syntax</a></li></ol></li><li class="expanded "><a href="ch19-00-advanced-features.html"><strong aria-hidden="true">19.</strong> Advanced Features</a></li><li><ol class="section"><li class="expanded "><a href="ch19-01-unsafe-rust.html"><strong aria-hidden="true">19.1.</strong> Unsafe Rust</a></li><li class="expanded "><a href="ch19-03-advanced-traits.html"><strong aria-hidden="true">19.2.</strong> Advanced Traits</a></li><li class="expanded "><a href="ch19-04-advanced-types.html"><strong aria-hidden="true">19.3.</strong> Advanced Types</a></li><li class="expanded "><a href="ch19-05-advanced-functions-and-closures.html"><strong aria-hidden="true">19.4.</strong> Advanced Functions and Closures</a></li><li class="expanded "><a href="ch19-06-macros.html"><strong aria-hidden="true">19.5.</strong> Macros</a></li></ol></li><li class="expanded "><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 class="expanded "><a href="ch20-01-single-threaded.html"><strong aria-hidden="true">20.1.</strong> Building a Single-Threaded Web Server</a></li><li class="expanded "><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 class="expanded "><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 class="expanded "><a href="appendix-00.html"><strong aria-hidden="true">21.</strong> Appendix</a></li><li><ol class="section"><li class="expanded "><a href="appendix-01-keywords.html"><strong aria-hidden="true">21.1.</strong> A - Keywords</a></li><li class="expanded "><a href="appendix-02-operators.html" class="active"><strong aria-hidden="true">21.2.</strong> B - Operators and Symbols</a></li><li class="expanded "><a href="appendix-03-derivable-traits.html"><strong aria-hidden="true">21.3.</strong> C - Derivable Traits</a></li><li class="expanded "><a href="appendix-04-useful-development-tools.html"><strong aria-hidden="true">21.4.</strong> D - Useful Development Tools</a></li><li class="expanded "><a href="appendix-05-editions.html"><strong aria-hidden="true">21.5.</strong> E - Editions</a></li><li class="expanded "><a href="appendix-06-translation.html"><strong aria-hidden="true">21.6.</strong> F - Translations of the Book</a></li><li class="expanded "><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>
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<h2><a class="header" href="#appendix-b-operators-and-symbols" id="appendix-b-operators-and-symbols">Appendix B: Operators and Symbols</a></h2>
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<p>This appendix contains a glossary of Rust’s syntax, including operators and
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other symbols that appear by themselves or in the context of paths, generics,
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trait bounds, macros, attributes, comments, tuples, and brackets.</p>
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<h3><a class="header" href="#operators" id="operators">Operators</a></h3>
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<p>Table B-1 contains the operators in Rust, an example of how the operator would
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appear in context, a short explanation, and whether that operator is
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overloadable. If an operator is overloadable, the relevant trait to use to
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overload that operator is listed.</p>
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<p><span class="caption">Table B-1: Operators</span></p>
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||
<table><thead><tr><th>Operator</th><th>Example</th><th>Explanation</th><th>Overloadable?</th></tr></thead><tbody>
|
||
<tr><td><code>!</code></td><td><code>ident!(...)</code>, <code>ident!{...}</code>, <code>ident![...]</code></td><td>Macro expansion</td><td></td></tr>
|
||
<tr><td><code>!</code></td><td><code>!expr</code></td><td>Bitwise or logical complement</td><td><code>Not</code></td></tr>
|
||
<tr><td><code>!=</code></td><td><code>var != expr</code></td><td>Nonequality comparison</td><td><code>PartialEq</code></td></tr>
|
||
<tr><td><code>%</code></td><td><code>expr % expr</code></td><td>Arithmetic remainder</td><td><code>Rem</code></td></tr>
|
||
<tr><td><code>%=</code></td><td><code>var %= expr</code></td><td>Arithmetic remainder and assignment</td><td><code>RemAssign</code></td></tr>
|
||
<tr><td><code>&</code></td><td><code>&expr</code>, <code>&mut expr</code></td><td>Borrow</td><td></td></tr>
|
||
<tr><td><code>&</code></td><td><code>&type</code>, <code>&mut type</code>, <code>&'a type</code>, <code>&'a mut type</code></td><td>Borrowed pointer type</td><td></td></tr>
|
||
<tr><td><code>&</code></td><td><code>expr & expr</code></td><td>Bitwise AND</td><td><code>BitAnd</code></td></tr>
|
||
<tr><td><code>&=</code></td><td><code>var &= expr</code></td><td>Bitwise AND and assignment</td><td><code>BitAndAssign</code></td></tr>
|
||
<tr><td><code>&&</code></td><td><code>expr && expr</code></td><td>Logical AND</td><td></td></tr>
|
||
<tr><td><code>*</code></td><td><code>expr * expr</code></td><td>Arithmetic multiplication</td><td><code>Mul</code></td></tr>
|
||
<tr><td><code>*=</code></td><td><code>var *= expr</code></td><td>Arithmetic multiplication and assignment</td><td><code>MulAssign</code></td></tr>
|
||
<tr><td><code>*</code></td><td><code>*expr</code></td><td>Dereference</td><td></td></tr>
|
||
<tr><td><code>*</code></td><td><code>*const type</code>, <code>*mut type</code></td><td>Raw pointer</td><td></td></tr>
|
||
<tr><td><code>+</code></td><td><code>trait + trait</code>, <code>'a + trait</code></td><td>Compound type constraint</td><td></td></tr>
|
||
<tr><td><code>+</code></td><td><code>expr + expr</code></td><td>Arithmetic addition</td><td><code>Add</code></td></tr>
|
||
<tr><td><code>+=</code></td><td><code>var += expr</code></td><td>Arithmetic addition and assignment</td><td><code>AddAssign</code></td></tr>
|
||
<tr><td><code>,</code></td><td><code>expr, expr</code></td><td>Argument and element separator</td><td></td></tr>
|
||
<tr><td><code>-</code></td><td><code>- expr</code></td><td>Arithmetic negation</td><td><code>Neg</code></td></tr>
|
||
<tr><td><code>-</code></td><td><code>expr - expr</code></td><td>Arithmetic subtraction</td><td><code>Sub</code></td></tr>
|
||
<tr><td><code>-=</code></td><td><code>var -= expr</code></td><td>Arithmetic subtraction and assignment</td><td><code>SubAssign</code></td></tr>
|
||
<tr><td><code>-></code></td><td><code>fn(...) -> type</code>, <code>|...| -> type</code></td><td>Function and closure return type</td><td></td></tr>
|
||
<tr><td><code>.</code></td><td><code>expr.ident</code></td><td>Member access</td><td></td></tr>
|
||
<tr><td><code>..</code></td><td><code>..</code>, <code>expr..</code>, <code>..expr</code>, <code>expr..expr</code></td><td>Right-exclusive range literal</td><td></td></tr>
|
||
<tr><td><code>..=</code></td><td><code>..=expr</code>, <code>expr..=expr</code></td><td>Right-inclusive range literal</td><td></td></tr>
|
||
<tr><td><code>..</code></td><td><code>..expr</code></td><td>Struct literal update syntax</td><td></td></tr>
|
||
<tr><td><code>..</code></td><td><code>variant(x, ..)</code>, <code>struct_type { x, .. }</code></td><td>“And the rest” pattern binding</td><td></td></tr>
|
||
<tr><td><code>...</code></td><td><code>expr...expr</code></td><td>In a pattern: inclusive range pattern</td><td></td></tr>
|
||
<tr><td><code>/</code></td><td><code>expr / expr</code></td><td>Arithmetic division</td><td><code>Div</code></td></tr>
|
||
<tr><td><code>/=</code></td><td><code>var /= expr</code></td><td>Arithmetic division and assignment</td><td><code>DivAssign</code></td></tr>
|
||
<tr><td><code>:</code></td><td><code>pat: type</code>, <code>ident: type</code></td><td>Constraints</td><td></td></tr>
|
||
<tr><td><code>:</code></td><td><code>ident: expr</code></td><td>Struct field initializer</td><td></td></tr>
|
||
<tr><td><code>:</code></td><td><code>'a: loop {...}</code></td><td>Loop label</td><td></td></tr>
|
||
<tr><td><code>;</code></td><td><code>expr;</code></td><td>Statement and item terminator</td><td></td></tr>
|
||
<tr><td><code>;</code></td><td><code>[...; len]</code></td><td>Part of fixed-size array syntax</td><td></td></tr>
|
||
<tr><td><code><<</code></td><td><code>expr << expr</code></td><td>Left-shift</td><td><code>Shl</code></td></tr>
|
||
<tr><td><code><<=</code></td><td><code>var <<= expr</code></td><td>Left-shift and assignment</td><td><code>ShlAssign</code></td></tr>
|
||
<tr><td><code><</code></td><td><code>expr < expr</code></td><td>Less than comparison</td><td><code>PartialOrd</code></td></tr>
|
||
<tr><td><code><=</code></td><td><code>expr <= expr</code></td><td>Less than or equal to comparison</td><td><code>PartialOrd</code></td></tr>
|
||
<tr><td><code>=</code></td><td><code>var = expr</code>, <code>ident = type</code></td><td>Assignment/equivalence</td><td></td></tr>
|
||
<tr><td><code>==</code></td><td><code>expr == expr</code></td><td>Equality comparison</td><td><code>PartialEq</code></td></tr>
|
||
<tr><td><code>=></code></td><td><code>pat => expr</code></td><td>Part of match arm syntax</td><td></td></tr>
|
||
<tr><td><code>></code></td><td><code>expr > expr</code></td><td>Greater than comparison</td><td><code>PartialOrd</code></td></tr>
|
||
<tr><td><code>>=</code></td><td><code>expr >= expr</code></td><td>Greater than or equal to comparison</td><td><code>PartialOrd</code></td></tr>
|
||
<tr><td><code>>></code></td><td><code>expr >> expr</code></td><td>Right-shift</td><td><code>Shr</code></td></tr>
|
||
<tr><td><code>>>=</code></td><td><code>var >>= expr</code></td><td>Right-shift and assignment</td><td><code>ShrAssign</code></td></tr>
|
||
<tr><td><code>@</code></td><td><code>ident @ pat</code></td><td>Pattern binding</td><td></td></tr>
|
||
<tr><td><code>^</code></td><td><code>expr ^ expr</code></td><td>Bitwise exclusive OR</td><td><code>BitXor</code></td></tr>
|
||
<tr><td><code>^=</code></td><td><code>var ^= expr</code></td><td>Bitwise exclusive OR and assignment</td><td><code>BitXorAssign</code></td></tr>
|
||
<tr><td><code>|</code></td><td><code>pat | pat</code></td><td>Pattern alternatives</td><td></td></tr>
|
||
<tr><td><code>|</code></td><td><code>expr | expr</code></td><td>Bitwise OR</td><td><code>BitOr</code></td></tr>
|
||
<tr><td><code>|=</code></td><td><code>var |= expr</code></td><td>Bitwise OR and assignment</td><td><code>BitOrAssign</code></td></tr>
|
||
<tr><td><code>||</code></td><td><code>expr || expr</code></td><td>Logical OR</td><td></td></tr>
|
||
<tr><td><code>?</code></td><td><code>expr?</code></td><td>Error propagation</td><td></td></tr>
|
||
</tbody></table>
|
||
<h3><a class="header" href="#non-operator-symbols" id="non-operator-symbols">Non-operator Symbols</a></h3>
|
||
<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>
|
||
<p>Table B-2 shows symbols that appear on their own and are valid in a variety of
|
||
locations.</p>
|
||
<p><span class="caption">Table B-2: Stand-Alone Syntax</span></p>
|
||
<table><thead><tr><th>Symbol</th><th>Explanation</th></tr></thead><tbody>
|
||
<tr><td><code>'ident</code></td><td>Named lifetime or loop label</td></tr>
|
||
<tr><td><code>...u8</code>, <code>...i32</code>, <code>...f64</code>, <code>...usize</code>, etc.</td><td>Numeric literal of specific type</td></tr>
|
||
<tr><td><code>"..."</code></td><td>String literal</td></tr>
|
||
<tr><td><code>r"..."</code>, <code>r#"..."#</code>, <code>r##"..."##</code>, etc.</td><td>Raw string literal, escape characters not processed</td></tr>
|
||
<tr><td><code>b"..."</code></td><td>Byte string literal; constructs a <code>[u8]</code> instead of a string</td></tr>
|
||
<tr><td><code>br"..."</code>, <code>br#"..."#</code>, <code>br##"..."##</code>, etc.</td><td>Raw byte string literal, combination of raw and byte string literal</td></tr>
|
||
<tr><td><code>'...'</code></td><td>Character literal</td></tr>
|
||
<tr><td><code>b'...'</code></td><td>ASCII byte literal</td></tr>
|
||
<tr><td><code>|...| expr</code></td><td>Closure</td></tr>
|
||
<tr><td><code>!</code></td><td>Always empty bottom type for diverging functions</td></tr>
|
||
<tr><td><code>_</code></td><td>“Ignored” pattern binding; also used to make integer literals readable</td></tr>
|
||
</tbody></table>
|
||
<p>Table B-3 shows symbols that appear in the context of a path through the module
|
||
hierarchy to an item.</p>
|
||
<p><span class="caption">Table B-3: Path-Related Syntax</span></p>
|
||
<table><thead><tr><th>Symbol</th><th>Explanation</th></tr></thead><tbody>
|
||
<tr><td><code>ident::ident</code></td><td>Namespace path</td></tr>
|
||
<tr><td><code>::path</code></td><td>Path relative to the crate root (i.e., an explicitly absolute path)</td></tr>
|
||
<tr><td><code>self::path</code></td><td>Path relative to the current module (i.e., an explicitly relative path).</td></tr>
|
||
<tr><td><code>super::path</code></td><td>Path relative to the parent of the current module</td></tr>
|
||
<tr><td><code>type::ident</code>, <code><type as trait>::ident</code></td><td>Associated constants, functions, and types</td></tr>
|
||
<tr><td><code><type>::...</code></td><td>Associated item for a type that cannot be directly named (e.g., <code><&T>::...</code>, <code><[T]>::...</code>, etc.)</td></tr>
|
||
<tr><td><code>trait::method(...)</code></td><td>Disambiguating a method call by naming the trait that defines it</td></tr>
|
||
<tr><td><code>type::method(...)</code></td><td>Disambiguating a method call by naming the type for which it’s defined</td></tr>
|
||
<tr><td><code><type as trait>::method(...)</code></td><td>Disambiguating a method call by naming the trait and type</td></tr>
|
||
</tbody></table>
|
||
<p>Table B-4 shows symbols that appear in the context of using generic type
|
||
parameters.</p>
|
||
<p><span class="caption">Table B-4: Generics</span></p>
|
||
<table><thead><tr><th>Symbol</th><th>Explanation</th></tr></thead><tbody>
|
||
<tr><td><code>path<...></code></td><td>Specifies parameters to generic type in a type (e.g., <code>Vec<u8></code>)</td></tr>
|
||
<tr><td><code>path::<...></code>, <code>method::<...></code></td><td>Specifies parameters to generic type, function, or method in an expression; often referred to as turbofish (e.g., <code>"42".parse::<i32>()</code>)</td></tr>
|
||
<tr><td><code>fn ident<...> ...</code></td><td>Define generic function</td></tr>
|
||
<tr><td><code>struct ident<...> ...</code></td><td>Define generic structure</td></tr>
|
||
<tr><td><code>enum ident<...> ...</code></td><td>Define generic enumeration</td></tr>
|
||
<tr><td><code>impl<...> ...</code></td><td>Define generic implementation</td></tr>
|
||
<tr><td><code>for<...> type</code></td><td>Higher-ranked lifetime bounds</td></tr>
|
||
<tr><td><code>type<ident=type></code></td><td>A generic type where one or more associated types have specific assignments (e.g., <code>Iterator<Item=T></code>)</td></tr>
|
||
</tbody></table>
|
||
<p>Table B-5 shows symbols that appear in the context of constraining generic type
|
||
parameters with trait bounds.</p>
|
||
<p><span class="caption">Table B-5: Trait Bound Constraints</span></p>
|
||
<table><thead><tr><th>Symbol</th><th>Explanation</th></tr></thead><tbody>
|
||
<tr><td><code>T: U</code></td><td>Generic parameter <code>T</code> constrained to types that implement <code>U</code></td></tr>
|
||
<tr><td><code>T: 'a</code></td><td>Generic type <code>T</code> must outlive lifetime <code>'a</code> (meaning the type cannot transitively contain any references with lifetimes shorter than <code>'a</code>)</td></tr>
|
||
<tr><td><code>T : 'static</code></td><td>Generic type <code>T</code> contains no borrowed references other than <code>'static</code> ones</td></tr>
|
||
<tr><td><code>'b: 'a</code></td><td>Generic lifetime <code>'b</code> must outlive lifetime <code>'a</code></td></tr>
|
||
<tr><td><code>T: ?Sized</code></td><td>Allow generic type parameter to be a dynamically sized type</td></tr>
|
||
<tr><td><code>'a + trait</code>, <code>trait + trait</code></td><td>Compound type constraint</td></tr>
|
||
</tbody></table>
|
||
<p>Table B-6 shows symbols that appear in the context of calling or defining
|
||
macros and specifying attributes on an item.</p>
|
||
<p><span class="caption">Table B-6: Macros and Attributes</span></p>
|
||
<table><thead><tr><th>Symbol</th><th>Explanation</th></tr></thead><tbody>
|
||
<tr><td><code>#[meta]</code></td><td>Outer attribute</td></tr>
|
||
<tr><td><code>#![meta]</code></td><td>Inner attribute</td></tr>
|
||
<tr><td><code>$ident</code></td><td>Macro substitution</td></tr>
|
||
<tr><td><code>$ident:kind</code></td><td>Macro capture</td></tr>
|
||
<tr><td><code>$(…)…</code></td><td>Macro repetition</td></tr>
|
||
</tbody></table>
|
||
<p>Table B-7 shows symbols that create comments.</p>
|
||
<p><span class="caption">Table B-7: Comments</span></p>
|
||
<table><thead><tr><th>Symbol</th><th>Explanation</th></tr></thead><tbody>
|
||
<tr><td><code>//</code></td><td>Line comment</td></tr>
|
||
<tr><td><code>//!</code></td><td>Inner line doc comment</td></tr>
|
||
<tr><td><code>///</code></td><td>Outer line doc comment</td></tr>
|
||
<tr><td><code>/*...*/</code></td><td>Block comment</td></tr>
|
||
<tr><td><code>/*!...*/</code></td><td>Inner block doc comment</td></tr>
|
||
<tr><td><code>/**...*/</code></td><td>Outer block doc comment</td></tr>
|
||
</tbody></table>
|
||
<p>Table B-8 shows symbols that appear in the context of using tuples.</p>
|
||
<p><span class="caption">Table B-8: Tuples</span></p>
|
||
<table><thead><tr><th>Symbol</th><th>Explanation</th></tr></thead><tbody>
|
||
<tr><td><code>()</code></td><td>Empty tuple (aka unit), both literal and type</td></tr>
|
||
<tr><td><code>(expr)</code></td><td>Parenthesized expression</td></tr>
|
||
<tr><td><code>(expr,)</code></td><td>Single-element tuple expression</td></tr>
|
||
<tr><td><code>(type,)</code></td><td>Single-element tuple type</td></tr>
|
||
<tr><td><code>(expr, ...)</code></td><td>Tuple expression</td></tr>
|
||
<tr><td><code>(type, ...)</code></td><td>Tuple type</td></tr>
|
||
<tr><td><code>expr(expr, ...)</code></td><td>Function call expression; also used to initialize tuple <code>struct</code>s and tuple <code>enum</code> variants</td></tr>
|
||
<tr><td><code>ident!(...)</code>, <code>ident!{...}</code>, <code>ident![...]</code></td><td>Macro invocation</td></tr>
|
||
<tr><td><code>expr.0</code>, <code>expr.1</code>, etc.</td><td>Tuple indexing</td></tr>
|
||
</tbody></table>
|
||
<p>Table B-9 shows the contexts in which curly braces are used.</p>
|
||
<p><span class="caption">Table B-9: Curly Brackets</span></p>
|
||
<table><thead><tr><th>Context</th><th>Explanation</th></tr></thead><tbody>
|
||
<tr><td><code>{...}</code></td><td>Block expression</td></tr>
|
||
<tr><td><code>Type {...}</code></td><td><code>struct</code> literal</td></tr>
|
||
</tbody></table>
|
||
<p>Table B-10 shows the contexts in which square brackets are used.</p>
|
||
<p><span class="caption">Table B-10: Square Brackets</span></p>
|
||
<table><thead><tr><th>Context</th><th>Explanation</th></tr></thead><tbody>
|
||
<tr><td><code>[...]</code></td><td>Array literal</td></tr>
|
||
<tr><td><code>[expr; len]</code></td><td>Array literal containing <code>len</code> copies of <code>expr</code></td></tr>
|
||
<tr><td><code>[type; len]</code></td><td>Array type containing <code>len</code> instances of <code>type</code></td></tr>
|
||
<tr><td><code>expr[expr]</code></td><td>Collection indexing. Overloadable (<code>Index</code>, <code>IndexMut</code>)</td></tr>
|
||
<tr><td><code>expr[..]</code>, <code>expr[a..]</code>, <code>expr[..b]</code>, <code>expr[a..b]</code></td><td>Collection indexing pretending to be collection slicing, using <code>Range</code>, <code>RangeFrom</code>, <code>RangeTo</code>, or <code>RangeFull</code> as the “index”</td></tr>
|
||
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