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<!DOCTYPE html> <html class="writer-html5" lang="en"> <head> <meta charset="utf-8" /><meta name="generator" content="Docutils 0.19: https://docutils.sourceforge.io/" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Solidity — Solidity 0.8.28 documentation</title> <link rel="stylesheet" type="text/css" href="_static/pygments.css" /> <link rel="stylesheet" type="text/css" href="_static/css/theme.css" /> <link rel="stylesheet" type="text/css" href="_static/a4_railroad_diagram.css" /> <link rel="stylesheet" type="text/css" href="_static/css/fonts.css" /> <link rel="stylesheet" type="text/css" href="_static/css/custom.css" /> <link rel="stylesheet" type="text/css" href="_static/css/custom-dark.css" /> <link rel="stylesheet" type="text/css" href="_static/css/pygments.css" /> <link rel="stylesheet" type="text/css" href="_static/css/toggle.css" /> <link rel="shortcut icon" href="_static/favicon.ico"/>  <script data-url_root="./" id="documentation_options" 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name="readthedocs-http-status" content="200" /></head> <body class="wy-body-for-nav"> <div class="wy-grid-for-nav"> <nav data-toggle="wy-nav-shift" class="wy-nav-side"> <div class="wy-side-scroll"> <div class="wy-side-nav-search" > <a href="#"> </a> <div class="version"> 0.8.28 </div> <div role="search"> <form id="rtd-search-form" class="wy-form" action="search.html" method="get"> <input type="text" name="q" placeholder="Search docs" aria-label="Search docs" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> </div><div class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="Navigation menu"> <p class="caption" role="heading"><span class="caption-text">Basics</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="introduction-to-smart-contracts.html">Introduction to Smart Contracts</a></li> <li class="toctree-l1"><a class="reference internal" href="solidity-by-example.html">Solidity by Example</a></li> <li class="toctree-l1"><a class="reference internal" href="installing-solidity.html">Installing the Solidity Compiler</a></li> </ul> <p class="caption" role="heading"><span class="caption-text">Language Description</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="layout-of-source-files.html">Layout of a Solidity Source File</a></li> <li class="toctree-l1"><a class="reference internal" href="structure-of-a-contract.html">Structure of a Contract</a></li> <li class="toctree-l1"><a class="reference internal" href="types.html">Types</a></li> <li class="toctree-l1"><a class="reference internal" href="units-and-global-variables.html">Units and Globally Available Variables</a></li> <li class="toctree-l1"><a class="reference internal" href="control-structures.html">Expressions and Control Structures</a></li> <li class="toctree-l1"><a class="reference internal" href="contracts.html">Contracts</a></li> <li class="toctree-l1"><a class="reference internal" href="assembly.html">Inline Assembly</a></li> <li class="toctree-l1"><a class="reference internal" href="cheatsheet.html">Cheatsheet</a></li> <li class="toctree-l1"><a class="reference internal" href="grammar.html">Language Grammar</a></li> </ul> <p class="caption" role="heading"><span class="caption-text">Compiler</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="using-the-compiler.html">Using the Compiler</a></li> <li class="toctree-l1"><a class="reference internal" href="analysing-compilation-output.html">Analysing the Compiler Output</a></li> <li class="toctree-l1"><a class="reference internal" href="ir-breaking-changes.html">Solidity IR-based Codegen Changes</a></li> </ul> <p class="caption" role="heading"><span class="caption-text">Internals</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="internals/layout_in_storage.html">Layout of State Variables in Storage and Transient Storage</a></li> <li class="toctree-l1"><a class="reference internal" href="internals/layout_in_memory.html">Layout in Memory</a></li> <li class="toctree-l1"><a class="reference internal" href="internals/layout_in_calldata.html">Layout of Call Data</a></li> <li class="toctree-l1"><a class="reference internal" href="internals/variable_cleanup.html">Cleaning Up Variables</a></li> <li class="toctree-l1"><a class="reference internal" href="internals/source_mappings.html">Source Mappings</a></li> <li class="toctree-l1"><a class="reference internal" href="internals/optimizer.html">The Optimizer</a></li> <li class="toctree-l1"><a class="reference internal" href="metadata.html">Contract Metadata</a></li> <li class="toctree-l1"><a class="reference internal" href="abi-spec.html">Contract ABI Specification</a></li> </ul> <p class="caption" role="heading"><span class="caption-text">Advisory content</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="security-considerations.html">Security Considerations</a></li> <li class="toctree-l1"><a class="reference internal" href="bugs.html">List of Known Bugs</a></li> <li class="toctree-l1"><a class="reference internal" href="050-breaking-changes.html">Solidity v0.5.0 Breaking Changes</a></li> <li class="toctree-l1"><a class="reference internal" href="060-breaking-changes.html">Solidity v0.6.0 Breaking Changes</a></li> <li class="toctree-l1"><a class="reference internal" href="070-breaking-changes.html">Solidity v0.7.0 Breaking Changes</a></li> <li class="toctree-l1"><a class="reference internal" href="080-breaking-changes.html">Solidity v0.8.0 Breaking Changes</a></li> </ul> <p class="caption" role="heading"><span class="caption-text">Additional Material</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="natspec-format.html">NatSpec Format</a></li> <li class="toctree-l1"><a class="reference internal" href="smtchecker.html">SMTChecker and Formal Verification</a></li> <li class="toctree-l1"><a class="reference internal" href="yul.html">Yul</a></li> <li class="toctree-l1"><a class="reference internal" href="path-resolution.html">Import Path Resolution</a></li> </ul> <p class="caption" role="heading"><span class="caption-text">Resources</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="style-guide.html">Style Guide</a></li> <li class="toctree-l1"><a class="reference internal" href="common-patterns.html">Common Patterns</a></li> <li class="toctree-l1"><a class="reference internal" href="resources.html">Resources</a></li> <li class="toctree-l1"><a class="reference internal" href="contributing.html">Contributing</a></li> <li class="toctree-l1"><a class="reference internal" href="language-influences.html">Language Influences</a></li> <li class="toctree-l1"><a class="reference internal" href="brand-guide.html">Solidity Brand Guide</a></li> </ul> <ul> <li> <a href="genindex.html">Keyword Index</a> </li> </ul> </div> </div> </nav> <section data-toggle="wy-nav-shift" class="wy-nav-content-wrap"><nav class="wy-nav-top" aria-label="Mobile navigation menu" > <i data-toggle="wy-nav-top" class="fa fa-bars"></i> <a href="#">Solidity</a> </nav> <div class="wy-nav-content"> <div class="rst-content"> <div role="navigation" aria-label="Page navigation"> <ul class="wy-breadcrumbs"> <li><a href="#" class="icon icon-home" aria-label="Home"></a></li> <li class="breadcrumb-item active">Solidity</li> <li class="wy-breadcrumbs-aside"> <a href="https://github.com/ethereum/solidity/blob/v0.8.28/docs/index.rst" class="fa fa-github"> Edit on GitHub</a> </li> </ul> <hr/> </div> <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article"> <div itemprop="articleBody"> <section id="solidity"> <h1>Solidity<a class="headerlink" href="#solidity" title="Permalink to this heading"></a></h1> <p>Solidity is an object-oriented, high-level language for implementing smart contracts. Smart contracts are programs that govern the behavior of accounts within the Ethereum state.</p> <p>Solidity is a <a class="reference external" href="https://en.wikipedia.org/wiki/List_of_programming_languages_by_type#Curly_bracket_languages">curly-bracket language</a> designed to target the Ethereum Virtual Machine (EVM). It is influenced by C++, Python, and JavaScript. You can find more details about which languages Solidity has been inspired by in the <a class="reference internal" href="language-influences.html"><span class="doc">language influences</span></a> section.</p> <p>Solidity is statically typed, supports inheritance, libraries, and complex user-defined types, among other features.</p> <p>With Solidity, you can create contracts for uses such as voting, crowdfunding, blind auctions, and multi-signature wallets.</p> <p>When deploying contracts, you should use the latest released version of Solidity. Apart from exceptional cases, only the latest version receives <a class="reference external" href="https://github.com/ethereum/solidity/security/policy#supported-versions">security fixes</a>. Furthermore, breaking changes, as well as new features, are introduced regularly. We currently use a 0.y.z version number <a class="reference external" href="https://semver.org/#spec-item-4">to indicate this fast pace of change</a>.</p> <div class="admonition warning"> <p class="admonition-title">Warning</p> <p>Solidity recently released the 0.8.x version that introduced a lot of breaking changes. Make sure you read <a class="reference internal" href="080-breaking-changes.html"><span class="doc">the full list</span></a>.</p> </div> <p>Ideas for improving Solidity or this documentation are always welcome, read our <a class="reference internal" href="contributing.html"><span class="doc">contributors guide</span></a> for more details.</p> <div class="admonition hint"> <p class="admonition-title">Hint</p> <p>You can download this documentation as PDF, HTML or Epub by clicking on the versions flyout menu in the bottom-left corner and selecting the preferred download format.</p> </div> <section id="getting-started"> <h2>Getting Started<a class="headerlink" href="#getting-started" title="Permalink to this heading"></a></h2> <p><strong>1. Understand the Smart Contract Basics</strong></p> <p>If you are new to the concept of smart contracts, we recommend you to get started by digging into the “Introduction to Smart Contracts” section, which covers the following:</p> <ul class="simple"> <li><p><a class="reference internal" href="introduction-to-smart-contracts.html#simple-smart-contract"><span class="std std-ref">A simple example smart contract</span></a> written in Solidity.</p></li> <li><p><a class="reference internal" href="introduction-to-smart-contracts.html#blockchain-basics"><span class="std std-ref">Blockchain Basics</span></a>.</p></li> <li><p><a class="reference internal" href="introduction-to-smart-contracts.html#the-ethereum-virtual-machine"><span class="std std-ref">The Ethereum Virtual Machine</span></a>.</p></li> </ul> <p><strong>2. Get to Know Solidity</strong></p> <p>Once you are accustomed to the basics, we recommend you read the <a class="reference internal" href="solidity-by-example.html"><span class="doc">“Solidity by Example”</span></a> and “Language Description” sections to understand the core concepts of the language.</p> <p><strong>3. Install the Solidity Compiler</strong></p> <p>There are various ways to install the Solidity compiler, simply choose your preferred option and follow the steps outlined on the <a class="reference internal" href="installing-solidity.html#installing-solidity"><span class="std std-ref">installation page</span></a>.</p> <div class="admonition hint"> <p class="admonition-title">Hint</p> <p>You can try out code examples directly in your browser with the <a class="reference external" href="https://remix.ethereum.org">Remix IDE</a>. Remix is a web browser-based IDE that allows you to write, deploy and administer Solidity smart contracts, without the need to install Solidity locally.</p> </div> <div class="admonition warning"> <p class="admonition-title">Warning</p> <p>As humans write software, it can have bugs. Therefore, you should follow established software development best practices when writing your smart contracts. This includes code review, testing, audits, and correctness proofs. Smart contract users are sometimes more confident with code than their authors, and blockchains and smart contracts have their own unique issues to watch out for, so before working on production code, make sure you read the <a class="reference internal" href="security-considerations.html#security-considerations"><span class="std std-ref">Security Considerations</span></a> section.</p> </div> <p><strong>4. Learn More</strong></p> <p>If you want to learn more about building decentralized applications on Ethereum, the <a class="reference external" href="https://ethereum.org/en/developers/">Ethereum Developer Resources</a> can help you with further general documentation around Ethereum, and a wide selection of tutorials, tools, and development frameworks.</p> <p>If you have any questions, you can try searching for answers or asking on the <a class="reference external" href="https://ethereum.stackexchange.com/">Ethereum StackExchange</a>, or our <a class="reference external" href="https://gitter.im/ethereum/solidity">Gitter channel</a>.</p> </section> <section id="translations"> <span id="id1"></span><h2>Translations<a class="headerlink" href="#translations" title="Permalink to this heading"></a></h2> <p>Community contributors help translate this documentation into several languages. Note that they have varying degrees of completeness and up-to-dateness. The English version stands as a reference.</p> <p>You can switch between languages by clicking on the flyout menu in the bottom-left corner and selecting the preferred language.</p> <ul class="simple"> <li><p><a class="reference external" href="https://docs.soliditylang.org/zh/latest/">Chinese</a></p></li> <li><p><a class="reference external" href="https://docs.soliditylang.org/fr/latest/">French</a></p></li> <li><p><a class="reference external" href="https://github.com/solidity-docs/id-indonesian">Indonesian</a></p></li> <li><p><a class="reference external" href="https://github.com/solidity-docs/ja-japanese">Japanese</a></p></li> <li><p><a class="reference external" href="https://github.com/solidity-docs/ko-korean">Korean</a></p></li> <li><p><a class="reference external" href="https://github.com/solidity-docs/fa-persian">Persian</a></p></li> <li><p><a class="reference external" href="https://github.com/solidity-docs/ru-russian">Russian</a></p></li> <li><p><a class="reference external" href="https://github.com/solidity-docs/es-spanish">Spanish</a></p></li> <li><p><a class="reference external" href="https://docs.soliditylang.org/tr/latest/">Turkish</a></p></li> </ul> <div class="admonition note"> <p class="admonition-title">Note</p> <p>We set up a GitHub organization and translation workflow to help streamline the community efforts. Please refer to the translation guide in the <a class="reference external" href="https://github.com/solidity-docs">solidity-docs org</a> for information on how to start a new language or contribute to the community translations.</p> </div> </section> </section> <section id="contents"> <h1>Contents<a class="headerlink" href="#contents" title="Permalink to this heading"></a></h1> <p><a class="reference internal" href="genindex.html"><span class="std std-ref">Keyword Index</span></a>, <a class="reference internal" href="search.html"><span class="std std-ref">Search Page</span></a></p> <div class="toctree-wrapper compound"> <p class="caption" role="heading"><span class="caption-text">Basics</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="introduction-to-smart-contracts.html">Introduction to Smart Contracts</a><ul> <li class="toctree-l2"><a class="reference internal" href="introduction-to-smart-contracts.html#a-simple-smart-contract">A Simple Smart Contract</a></li> <li class="toctree-l2"><a class="reference internal" href="introduction-to-smart-contracts.html#blockchain-basics">Blockchain Basics</a></li> <li class="toctree-l2"><a class="reference internal" href="introduction-to-smart-contracts.html#index-6">The Ethereum Virtual Machine</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="solidity-by-example.html">Solidity by Example</a><ul> <li class="toctree-l2"><a class="reference internal" href="solidity-by-example.html#voting">Voting</a></li> <li class="toctree-l2"><a class="reference internal" href="solidity-by-example.html#blind-auction">Blind Auction</a></li> <li class="toctree-l2"><a class="reference internal" href="solidity-by-example.html#safe-remote-purchase">Safe Remote Purchase</a></li> <li class="toctree-l2"><a class="reference internal" href="solidity-by-example.html#micropayment-channel">Micropayment Channel</a></li> <li class="toctree-l2"><a class="reference internal" href="solidity-by-example.html#modular-contracts">Modular Contracts</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="installing-solidity.html">Installing the Solidity Compiler</a><ul> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#versioning">Versioning</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#remix">Remix</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#npm-node-js">npm / Node.js</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#docker">Docker</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#linux-packages">Linux Packages</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#macos-packages">macOS Packages</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#static-binaries">Static Binaries</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#building-from-source">Building from Source</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#cmake-options">CMake Options</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#the-version-string-in-detail">The Version String in Detail</a></li> <li class="toctree-l2"><a class="reference internal" href="installing-solidity.html#important-information-about-versioning">Important Information About Versioning</a></li> </ul> </li> </ul> </div> <div class="toctree-wrapper compound"> <p class="caption" role="heading"><span class="caption-text">Language Description</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="layout-of-source-files.html">Layout of a Solidity Source File</a><ul> <li class="toctree-l2"><a class="reference internal" href="layout-of-source-files.html#spdx-license-identifier">SPDX License Identifier</a></li> <li class="toctree-l2"><a class="reference internal" href="layout-of-source-files.html#pragmas">Pragmas</a></li> <li class="toctree-l2"><a class="reference internal" href="layout-of-source-files.html#importing-other-source-files">Importing other Source Files</a></li> <li class="toctree-l2"><a class="reference internal" href="layout-of-source-files.html#comments">Comments</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="structure-of-a-contract.html">Structure of a Contract</a><ul> <li class="toctree-l2"><a class="reference internal" href="structure-of-a-contract.html#state-variables">State Variables</a></li> <li class="toctree-l2"><a class="reference internal" href="structure-of-a-contract.html#functions">Functions</a></li> <li class="toctree-l2"><a class="reference internal" href="structure-of-a-contract.html#function-modifiers">Function Modifiers</a></li> <li class="toctree-l2"><a class="reference internal" href="structure-of-a-contract.html#events">Events</a></li> <li class="toctree-l2"><a class="reference internal" href="structure-of-a-contract.html#errors">Errors</a></li> <li class="toctree-l2"><a class="reference internal" href="structure-of-a-contract.html#struct-types">Struct Types</a></li> <li class="toctree-l2"><a class="reference internal" href="structure-of-a-contract.html#enum-types">Enum Types</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="types.html">Types</a><ul> <li class="toctree-l2"><a class="reference internal" href="types.html#value-types">Value Types</a></li> <li class="toctree-l2"><a class="reference internal" href="types.html#reference-types">Reference Types</a></li> <li class="toctree-l2"><a class="reference internal" href="types.html#mapping-types">Mapping Types</a></li> <li class="toctree-l2"><a class="reference internal" href="types.html#operators">Operators</a></li> <li class="toctree-l2"><a class="reference internal" href="types.html#conversions-between-elementary-types">Conversions between Elementary Types</a></li> <li class="toctree-l2"><a class="reference internal" href="types.html#conversions-between-literals-and-elementary-types">Conversions between Literals and Elementary Types</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="units-and-global-variables.html">Units and Globally Available Variables</a><ul> <li class="toctree-l2"><a class="reference internal" href="units-and-global-variables.html#ether-units">Ether Units</a></li> <li class="toctree-l2"><a class="reference internal" href="units-and-global-variables.html#time-units">Time Units</a></li> <li class="toctree-l2"><a class="reference internal" href="units-and-global-variables.html#special-variables-and-functions">Special Variables and Functions</a></li> <li class="toctree-l2"><a class="reference internal" href="units-and-global-variables.html#reserved-keywords">Reserved Keywords</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="control-structures.html">Expressions and Control Structures</a><ul> <li class="toctree-l2"><a class="reference internal" href="control-structures.html#control-structures">Control Structures</a></li> <li class="toctree-l2"><a class="reference internal" href="control-structures.html#function-calls">Function Calls</a></li> <li class="toctree-l2"><a class="reference internal" href="control-structures.html#creating-contracts-via-new">Creating Contracts via <code class="docutils literal notranslate"><span class="pre">new</span></code></a></li> <li class="toctree-l2"><a class="reference internal" href="control-structures.html#order-of-evaluation-of-expressions">Order of Evaluation of Expressions</a></li> <li class="toctree-l2"><a class="reference internal" href="control-structures.html#assignment">Assignment</a></li> <li class="toctree-l2"><a class="reference internal" href="control-structures.html#scoping-and-declarations">Scoping and Declarations</a></li> <li class="toctree-l2"><a class="reference internal" href="control-structures.html#checked-or-unchecked-arithmetic">Checked or Unchecked Arithmetic</a></li> <li class="toctree-l2"><a class="reference internal" href="control-structures.html#error-handling-assert-require-revert-and-exceptions">Error handling: Assert, Require, Revert and Exceptions</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="contracts.html">Contracts</a><ul> <li class="toctree-l2"><a class="reference internal" href="contracts.html#creating-contracts">Creating Contracts</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#visibility-and-getters">Visibility and Getters</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#function-modifiers">Function Modifiers</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#transient-storage">Transient Storage</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#composability-of-smart-contracts-and-the-caveats-of-transient-storage">Composability of Smart Contracts and the Caveats of Transient Storage</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#constant-and-immutable-state-variables">Constant and Immutable State Variables</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#functions">Functions</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#events">Events</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#custom-errors">Custom Errors</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#inheritance">Inheritance</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#abstract-contracts">Abstract Contracts</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#interfaces">Interfaces</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#libraries">Libraries</a></li> <li class="toctree-l2"><a class="reference internal" href="contracts.html#using-for">Using For</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="assembly.html">Inline Assembly</a><ul> <li class="toctree-l2"><a class="reference internal" href="assembly.html#example">Example</a></li> <li class="toctree-l2"><a class="reference internal" href="assembly.html#access-to-external-variables-functions-and-libraries">Access to External Variables, Functions and Libraries</a></li> <li class="toctree-l2"><a class="reference internal" href="assembly.html#things-to-avoid">Things to Avoid</a></li> <li class="toctree-l2"><a class="reference internal" href="assembly.html#conventions-in-solidity">Conventions in Solidity</a></li> <li class="toctree-l2"><a class="reference internal" href="assembly.html#advanced-safe-use-of-memory">Advanced Safe Use of Memory</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="cheatsheet.html">Cheatsheet</a><ul> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#order-of-precedence-of-operators">Order of Precedence of Operators</a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#abi-encoding-and-decoding-functions">ABI Encoding and Decoding Functions</a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#members-of-bytes-and-string">Members of <code class="docutils literal notranslate"><span class="pre">bytes</span></code> and <code class="docutils literal notranslate"><span class="pre">string</span></code></a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#members-of-address">Members of <code class="docutils literal notranslate"><span class="pre">address</span></code></a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#block-and-transaction-properties">Block and Transaction Properties</a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#validations-and-assertions">Validations and Assertions</a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#mathematical-and-cryptographic-functions">Mathematical and Cryptographic Functions</a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#contract-related">Contract-related</a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#type-information">Type Information</a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#function-visibility-specifiers">Function Visibility Specifiers</a></li> <li class="toctree-l2"><a class="reference internal" href="cheatsheet.html#modifiers">Modifiers</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="grammar.html">Language Grammar</a></li> </ul> </div> <div class="toctree-wrapper compound"> <p class="caption" role="heading"><span class="caption-text">Compiler</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="using-the-compiler.html">Using the Compiler</a><ul> <li class="toctree-l2"><a class="reference internal" href="using-the-compiler.html#using-the-commandline-compiler">Using the Commandline Compiler</a></li> <li class="toctree-l2"><a class="reference internal" href="using-the-compiler.html#setting-the-evm-version-to-target">Setting the EVM Version to Target</a></li> <li class="toctree-l2"><a class="reference internal" href="using-the-compiler.html#compiler-input-and-output-json-description">Compiler Input and Output JSON Description</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="analysing-compilation-output.html">Analysing the Compiler Output</a></li> <li class="toctree-l1"><a class="reference internal" href="ir-breaking-changes.html">Solidity IR-based Codegen Changes</a><ul> <li class="toctree-l2"><a class="reference internal" href="ir-breaking-changes.html#semantic-only-changes">Semantic Only Changes</a></li> <li class="toctree-l2"><a class="reference internal" href="ir-breaking-changes.html#internals">Internals</a></li> </ul> </li> </ul> </div> <div class="toctree-wrapper compound"> <p class="caption" role="heading"><span class="caption-text">Internals</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="internals/layout_in_storage.html">Layout of State Variables in Storage and Transient Storage</a><ul> <li class="toctree-l2"><a class="reference internal" href="internals/layout_in_storage.html#mappings-and-dynamic-arrays">Mappings and Dynamic Arrays</a></li> <li class="toctree-l2"><a class="reference internal" href="internals/layout_in_storage.html#json-output">JSON Output</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="internals/layout_in_memory.html">Layout in Memory</a><ul> <li class="toctree-l2"><a class="reference internal" href="internals/layout_in_memory.html#differences-to-layout-in-storage">Differences to Layout in Storage</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="internals/layout_in_calldata.html">Layout of Call Data</a></li> <li class="toctree-l1"><a class="reference internal" href="internals/variable_cleanup.html">Cleaning Up Variables</a></li> <li class="toctree-l1"><a class="reference internal" href="internals/source_mappings.html">Source Mappings</a></li> <li class="toctree-l1"><a class="reference internal" href="internals/optimizer.html">The Optimizer</a><ul> <li class="toctree-l2"><a class="reference internal" href="internals/optimizer.html#benefits-of-optimizing-solidity-code">Benefits of Optimizing Solidity Code</a></li> <li class="toctree-l2"><a class="reference internal" href="internals/optimizer.html#differences-between-optimized-and-non-optimized-code">Differences between Optimized and Non-Optimized Code</a></li> <li class="toctree-l2"><a class="reference internal" href="internals/optimizer.html#optimizer-parameter-runs">Optimizer Parameter Runs</a></li> <li class="toctree-l2"><a class="reference internal" href="internals/optimizer.html#opcode-based-optimizer-module">Opcode-Based Optimizer Module</a></li> <li class="toctree-l2"><a class="reference internal" href="internals/optimizer.html#yul-based-optimizer-module">Yul-Based Optimizer Module</a></li> <li class="toctree-l2"><a class="reference internal" href="internals/optimizer.html#codegen-based-optimizer-module">Codegen-Based Optimizer Module</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="metadata.html">Contract Metadata</a><ul> <li class="toctree-l2"><a class="reference internal" href="metadata.html#encoding-of-the-metadata-hash-in-the-bytecode">Encoding of the Metadata Hash in the Bytecode</a></li> <li class="toctree-l2"><a class="reference internal" href="metadata.html#usage-for-automatic-interface-generation-and-natspec">Usage for Automatic Interface Generation and NatSpec</a></li> <li class="toctree-l2"><a class="reference internal" href="metadata.html#usage-for-source-code-verification">Usage for Source Code Verification</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="abi-spec.html">Contract ABI Specification</a><ul> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#basic-design">Basic Design</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#function-selector">Function Selector</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#argument-encoding">Argument Encoding</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#types">Types</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#design-criteria-for-the-encoding">Design Criteria for the Encoding</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#formal-specification-of-the-encoding">Formal Specification of the Encoding</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#function-selector-and-argument-encoding">Function Selector and Argument Encoding</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#examples">Examples</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#use-of-dynamic-types">Use of Dynamic Types</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#events">Events</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#errors">Errors</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#json">JSON</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#strict-encoding-mode">Strict Encoding Mode</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#non-standard-packed-mode">Non-standard Packed Mode</a></li> <li class="toctree-l2"><a class="reference internal" href="abi-spec.html#encoding-of-indexed-event-parameters">Encoding of Indexed Event Parameters</a></li> </ul> </li> </ul> </div> <div class="toctree-wrapper compound"> <p class="caption" role="heading"><span class="caption-text">Advisory content</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="security-considerations.html">Security Considerations</a><ul> <li class="toctree-l2"><a class="reference internal" href="security-considerations.html#pitfalls">Pitfalls</a></li> <li class="toctree-l2"><a class="reference internal" href="security-considerations.html#recommendations">Recommendations</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="bugs.html">List of Known Bugs</a></li> <li class="toctree-l1"><a class="reference internal" href="050-breaking-changes.html">Solidity v0.5.0 Breaking Changes</a><ul> <li class="toctree-l2"><a class="reference internal" href="050-breaking-changes.html#semantic-only-changes">Semantic Only Changes</a></li> <li class="toctree-l2"><a class="reference internal" href="050-breaking-changes.html#semantic-and-syntactic-changes">Semantic and Syntactic Changes</a></li> <li class="toctree-l2"><a class="reference internal" href="050-breaking-changes.html#explicitness-requirements">Explicitness Requirements</a></li> <li class="toctree-l2"><a class="reference internal" href="050-breaking-changes.html#deprecated-elements">Deprecated Elements</a></li> <li class="toctree-l2"><a class="reference internal" href="050-breaking-changes.html#interoperability-with-older-contracts">Interoperability With Older Contracts</a></li> <li class="toctree-l2"><a class="reference internal" href="050-breaking-changes.html#example">Example</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="060-breaking-changes.html">Solidity v0.6.0 Breaking Changes</a><ul> <li class="toctree-l2"><a class="reference internal" href="060-breaking-changes.html#changes-the-compiler-might-not-warn-about">Changes the Compiler Might not Warn About</a></li> <li class="toctree-l2"><a class="reference internal" href="060-breaking-changes.html#explicitness-requirements">Explicitness Requirements</a></li> <li class="toctree-l2"><a class="reference internal" href="060-breaking-changes.html#semantic-and-syntactic-changes">Semantic and Syntactic Changes</a></li> <li class="toctree-l2"><a class="reference internal" href="060-breaking-changes.html#new-features">New Features</a></li> <li class="toctree-l2"><a class="reference internal" href="060-breaking-changes.html#interface-changes">Interface Changes</a></li> <li class="toctree-l2"><a class="reference internal" href="060-breaking-changes.html#how-to-update-your-code">How to update your code</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="070-breaking-changes.html">Solidity v0.7.0 Breaking Changes</a><ul> <li class="toctree-l2"><a class="reference internal" href="070-breaking-changes.html#silent-changes-of-the-semantics">Silent Changes of the Semantics</a></li> <li class="toctree-l2"><a class="reference internal" href="070-breaking-changes.html#changes-to-the-syntax">Changes to the Syntax</a></li> <li class="toctree-l2"><a class="reference internal" href="070-breaking-changes.html#removal-of-unused-or-unsafe-features">Removal of Unused or Unsafe Features</a></li> <li class="toctree-l2"><a class="reference internal" href="070-breaking-changes.html#interface-changes">Interface Changes</a></li> <li class="toctree-l2"><a class="reference internal" href="070-breaking-changes.html#how-to-update-your-code">How to update your code</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="080-breaking-changes.html">Solidity v0.8.0 Breaking Changes</a><ul> <li class="toctree-l2"><a class="reference internal" href="080-breaking-changes.html#silent-changes-of-the-semantics">Silent Changes of the Semantics</a></li> <li class="toctree-l2"><a class="reference internal" href="080-breaking-changes.html#new-restrictions">New Restrictions</a></li> <li class="toctree-l2"><a class="reference internal" href="080-breaking-changes.html#interface-changes">Interface Changes</a></li> <li class="toctree-l2"><a class="reference internal" href="080-breaking-changes.html#how-to-update-your-code">How to update your code</a></li> </ul> </li> </ul> </div> <div class="toctree-wrapper compound"> <p class="caption" role="heading"><span class="caption-text">Additional Material</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="natspec-format.html">NatSpec Format</a><ul> <li class="toctree-l2"><a class="reference internal" href="natspec-format.html#documentation-example">Documentation Example</a></li> <li class="toctree-l2"><a class="reference internal" href="natspec-format.html#tags">Tags</a></li> <li class="toctree-l2"><a class="reference internal" href="natspec-format.html#documentation-output">Documentation Output</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="smtchecker.html">SMTChecker and Formal Verification</a><ul> <li class="toctree-l2"><a class="reference internal" href="smtchecker.html#tutorial">Tutorial</a></li> <li class="toctree-l2"><a class="reference internal" href="smtchecker.html#smtchecker-options-and-tuning">SMTChecker Options and Tuning</a></li> <li class="toctree-l2"><a class="reference internal" href="smtchecker.html#abstraction-and-false-positives">Abstraction and False Positives</a></li> <li class="toctree-l2"><a class="reference internal" href="smtchecker.html#real-world-assumptions">Real World Assumptions</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="yul.html">Yul</a><ul> <li class="toctree-l2"><a class="reference internal" href="yul.html#motivation-and-high-level-description">Motivation and High-level Description</a></li> <li class="toctree-l2"><a class="reference internal" href="yul.html#simple-example">Simple Example</a></li> <li class="toctree-l2"><a class="reference internal" href="yul.html#stand-alone-usage">Stand-Alone Usage</a></li> <li class="toctree-l2"><a class="reference internal" href="yul.html#informal-description-of-yul">Informal Description of Yul</a></li> <li class="toctree-l2"><a class="reference internal" href="yul.html#specification-of-yul">Specification of Yul</a></li> <li class="toctree-l2"><a class="reference internal" href="yul.html#specification-of-yul-object">Specification of Yul Object</a></li> <li class="toctree-l2"><a class="reference internal" href="yul.html#yul-optimizer">Yul Optimizer</a></li> <li class="toctree-l2"><a class="reference internal" href="yul.html#complete-erc20-example">Complete ERC20 Example</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="path-resolution.html">Import Path Resolution</a><ul> <li class="toctree-l2"><a class="reference internal" href="path-resolution.html#virtual-filesystem">Virtual Filesystem</a></li> <li class="toctree-l2"><a class="reference internal" href="path-resolution.html#imports">Imports</a></li> <li class="toctree-l2"><a class="reference internal" href="path-resolution.html#base-path-and-include-paths">Base Path and Include Paths</a></li> <li class="toctree-l2"><a class="reference internal" href="path-resolution.html#allowed-paths">Allowed Paths</a></li> <li class="toctree-l2"><a class="reference internal" href="path-resolution.html#import-remapping">Import Remapping</a></li> <li class="toctree-l2"><a class="reference internal" href="path-resolution.html#using-urls-in-imports">Using URLs in imports</a></li> </ul> </li> </ul> 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href="common-patterns.html#withdrawal-from-contracts">Withdrawal from Contracts</a></li> <li class="toctree-l2"><a class="reference internal" href="common-patterns.html#restricting-access">Restricting Access</a></li> <li class="toctree-l2"><a class="reference internal" href="common-patterns.html#state-machine">State Machine</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="resources.html">Resources</a><ul> <li class="toctree-l2"><a class="reference internal" href="resources.html#general-resources">General Resources</a></li> <li class="toctree-l2"><a class="reference internal" href="resources.html#integrated-ethereum-development-environments">Integrated (Ethereum) Development Environments</a></li> <li class="toctree-l2"><a class="reference internal" href="resources.html#editor-integrations">Editor Integrations</a></li> <li class="toctree-l2"><a class="reference internal" href="resources.html#solidity-tools">Solidity Tools</a></li> <li class="toctree-l2"><a 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