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123 lines
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<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></div> <!----></nav> <ul class="sidebar-links"><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>Getting Started</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/anchor/getting-started/introduction.html" class="sidebar-link">Introduction</a></li><li><a href="/anchor/getting-started/installation.html" class="sidebar-link">Installing Dependencies</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>Teams</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/anchor/getting-started/projects.html" class="sidebar-link">Projects</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading open"><span>Tutorials</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/anchor/tutorials/tutorial-0.html" class="sidebar-link">A Minimal Example</a></li><li><a href="/anchor/tutorials/tutorial-1.html" aria-current="page" class="active sidebar-link">Arguments and Accounts</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/anchor/tutorials/tutorial-1.html#clone-the-repo" class="sidebar-link">Clone the Repo</a></li><li class="sidebar-sub-header"><a href="/anchor/tutorials/tutorial-1.html#defining-a-program" class="sidebar-link">Defining a Program</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/anchor/tutorials/tutorial-1.html#initialize-instruction" class="sidebar-link">initialize instruction</a></li><li class="sidebar-sub-header"><a href="/anchor/tutorials/tutorial-1.html#update-instruction" class="sidebar-link">update instruction</a></li></ul></li><li class="sidebar-sub-header"><a href="/anchor/tutorials/tutorial-1.html#creating-and-initializing-accounts" class="sidebar-link">Creating and Initializing Accounts</a></li><li class="sidebar-sub-header"><a href="/anchor/tutorials/tutorial-1.html#next-steps" class="sidebar-link">Next Steps</a></li></ul></li><li><a href="/anchor/tutorials/tutorial-2.html" class="sidebar-link">Account Constraints and Access Control</a></li><li><a href="/anchor/tutorials/tutorial-3.html" class="sidebar-link">Cross Program Invocations (CPI)</a></li><li><a href="/anchor/tutorials/tutorial-4.html" class="sidebar-link">Errors</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>CLI</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/anchor/cli/commands.html" class="sidebar-link">Commands</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>Source Verification</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/anchor/getting-started/verification.html" class="sidebar-link">Verifiable Builds</a></li><li><a href="/anchor/getting-started/publishing.html" class="sidebar-link">Publishing Source</a></li></ul></section></li></ul> </aside> <main class="page"> <div class="theme-default-content content__default"><h1 id="arguments-and-accounts"><a href="#arguments-and-accounts" class="header-anchor">#</a> Arguments and Accounts</h1> <p>This tutorial covers the basics of creating and mutating accounts using Anchor.
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It's recommended to read <a href="/anchor/tutorials/tutorial-0.html">Tutorial 0</a> first, as this tutorial will
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build on top of it.</p> <h2 id="clone-the-repo"><a href="#clone-the-repo" class="header-anchor">#</a> Clone the Repo</h2> <p>To get started, clone the repo.</p> <div class="language-bash extra-class"><pre class="language-bash"><code><span class="token function">git</span> clone https://github.com/project-serum/anchor
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</code></pre></div><p>Change directories to the <a href="https://github.com/project-serum/anchor/tree/master/examples/tutorial/basic-1" target="_blank" rel="noopener noreferrer">example<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a>.</p> <div class="language-bash extra-class"><pre class="language-bash"><code><span class="token builtin class-name">cd</span> anchor/examples/tutorial/basic-1
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</code></pre></div><p>And install any additional JavaScript dependencies:</p> <div class="language-bash extra-class"><pre class="language-bash"><code><span class="token function">yarn</span> <span class="token function">install</span>
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</code></pre></div><h2 id="defining-a-program"><a href="#defining-a-program" class="header-anchor">#</a> Defining a Program</h2> <p>We define our program as follows</p> <div class="language-rs extra-class"><pre class="language-rs"><code><span class="token keyword">use</span> <span class="token namespace">anchor_lang<span class="token punctuation">::</span>prelude<span class="token punctuation">::</span></span><span class="token operator">*</span><span class="token punctuation">;</span>
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<span class="token macro property">declare_id!</span><span class="token punctuation">(</span><span class="token string">"Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
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<span class="token attribute attr-name">#[program]</span>
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<span class="token keyword">mod</span> <span class="token module-declaration namespace">basic_1</span> <span class="token punctuation">{</span>
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<span class="token keyword">use</span> <span class="token keyword">super</span><span class="token punctuation">::</span><span class="token operator">*</span><span class="token punctuation">;</span>
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<span class="token keyword">pub</span> <span class="token keyword">fn</span> <span class="token function-definition function">initialize</span><span class="token punctuation">(</span>ctx<span class="token punctuation">:</span> <span class="token class-name">Context</span><span class="token operator"><</span><span class="token class-name">Initialize</span><span class="token operator">></span><span class="token punctuation">,</span> data<span class="token punctuation">:</span> <span class="token keyword">u64</span><span class="token punctuation">)</span> <span class="token punctuation">-></span> <span class="token class-name">Result</span><span class="token operator"><</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">></span> <span class="token punctuation">{</span>
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<span class="token keyword">let</span> my_account <span class="token operator">=</span> <span class="token operator">&</span><span class="token keyword">mut</span> ctx<span class="token punctuation">.</span>accounts<span class="token punctuation">.</span>my_account<span class="token punctuation">;</span>
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my_account<span class="token punctuation">.</span>data <span class="token operator">=</span> data<span class="token punctuation">;</span>
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<span class="token class-name">Ok</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
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<span class="token punctuation">}</span>
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<span class="token keyword">pub</span> <span class="token keyword">fn</span> <span class="token function-definition function">update</span><span class="token punctuation">(</span>ctx<span class="token punctuation">:</span> <span class="token class-name">Context</span><span class="token operator"><</span><span class="token class-name">Update</span><span class="token operator">></span><span class="token punctuation">,</span> data<span class="token punctuation">:</span> <span class="token keyword">u64</span><span class="token punctuation">)</span> <span class="token punctuation">-></span> <span class="token class-name">Result</span><span class="token operator"><</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">></span> <span class="token punctuation">{</span>
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<span class="token keyword">let</span> my_account <span class="token operator">=</span> <span class="token operator">&</span><span class="token keyword">mut</span> ctx<span class="token punctuation">.</span>accounts<span class="token punctuation">.</span>my_account<span class="token punctuation">;</span>
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my_account<span class="token punctuation">.</span>data <span class="token operator">=</span> data<span class="token punctuation">;</span>
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<span class="token class-name">Ok</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
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<span class="token punctuation">}</span>
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<span class="token punctuation">}</span>
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<span class="token attribute attr-name">#[derive(Accounts)]</span>
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<span class="token keyword">pub</span> <span class="token keyword">struct</span> <span class="token type-definition class-name">Initialize</span><span class="token operator"><</span><span class="token lifetime-annotation symbol">'info</span><span class="token operator">></span> <span class="token punctuation">{</span>
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<span class="token attribute attr-name">#[account(init, payer = user, space = 8 + 8)]</span>
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<span class="token keyword">pub</span> my_account<span class="token punctuation">:</span> <span class="token class-name">Account</span><span class="token operator"><</span><span class="token lifetime-annotation symbol">'info</span><span class="token punctuation">,</span> <span class="token class-name">MyAccount</span><span class="token operator">></span><span class="token punctuation">,</span>
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<span class="token attribute attr-name">#[account(mut)]</span>
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<span class="token keyword">pub</span> user<span class="token punctuation">:</span> <span class="token class-name">Signer</span><span class="token operator"><</span><span class="token lifetime-annotation symbol">'info</span><span class="token operator">></span><span class="token punctuation">,</span>
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<span class="token keyword">pub</span> system_program<span class="token punctuation">:</span> <span class="token class-name">Program</span><span class="token operator"><</span><span class="token lifetime-annotation symbol">'info</span><span class="token punctuation">,</span> <span class="token class-name">System</span><span class="token operator">></span><span class="token punctuation">,</span>
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<span class="token punctuation">}</span>
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<span class="token attribute attr-name">#[derive(Accounts)]</span>
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<span class="token keyword">pub</span> <span class="token keyword">struct</span> <span class="token type-definition class-name">Update</span><span class="token operator"><</span><span class="token lifetime-annotation symbol">'info</span><span class="token operator">></span> <span class="token punctuation">{</span>
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<span class="token attribute attr-name">#[account(mut)]</span>
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<span class="token keyword">pub</span> my_account<span class="token punctuation">:</span> <span class="token class-name">Account</span><span class="token operator"><</span><span class="token lifetime-annotation symbol">'info</span><span class="token punctuation">,</span> <span class="token class-name">MyAccount</span><span class="token operator">></span><span class="token punctuation">,</span>
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<span class="token punctuation">}</span>
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<span class="token attribute attr-name">#[account]</span>
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<span class="token keyword">pub</span> <span class="token keyword">struct</span> <span class="token type-definition class-name">MyAccount</span> <span class="token punctuation">{</span>
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<span class="token keyword">pub</span> data<span class="token punctuation">:</span> <span class="token keyword">u64</span><span class="token punctuation">,</span>
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<span class="token punctuation">}</span>
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</code></pre></div><p>Some new syntax elements are introduced here.</p> <h3 id="initialize-instruction"><a href="#initialize-instruction" class="header-anchor">#</a> <code>initialize</code> instruction</h3> <p>First, let's start with the initialize instruction. Notice the <code>data</code> argument passed into the program. This argument and any other valid
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Rust types can be passed to the instruction to define inputs to the program.</p> <p>Additionally,
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notice how we take a mutable reference to <code>my_account</code> and assign the <code>data</code> to it. This leads us to
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the <code>Initialize</code> struct, deriving <code>Accounts</code>. There are two things to notice about <code>Initialize</code>.</p> <ol><li>The <code>my_account</code> field is of type <code>Account<'info, MyAccount></code> and the deserialized data structure is <code>MyAccount</code>.</li> <li>The <code>my_account</code> field is marked with the <code>init</code> attribute. This will create a new
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account owned by the current program, zero initialized. When using <code>init</code>, one must also provide
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<code>payer</code>, which will fund the account creation, <code>space</code>, which defines how large the account should be,
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and the <code>system_program</code>, which is required by the runtime for creating the account.</li></ol> <details class="custom-block details"><summary>DETAILS</summary> <p>All accounts created with Anchor are laid out as follows: <code>8-byte-discriminator || borsh serialized data</code>. The 8-byte-discriminator is created from the first 8 bytes of the
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<code>Sha256</code> hash of the account's type--using the example above, <code>sha256("account:MyAccount")[..8]</code>.
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The <code>account:</code> is a fixed prefix.</p> <p>Importantly, this allows a program to know for certain an account is indeed of a given type.
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Without it, a program would be vulnerable to account injection attacks, where a malicious user
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specifies an account of an unexpected type, causing the program to do unexpected things.</p> <p>On account creation, this 8-byte discriminator doesn't exist, since the account storage is
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zeroed. The first time an Anchor program mutates an account, this discriminator is prepended
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to the account storage array and all subsequent accesses to the account (not decorated with
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<code>#[account(init)]</code>) will check for this discriminator.</p></details> <h3 id="update-instruction"><a href="#update-instruction" class="header-anchor">#</a> <code>update</code> instruction</h3> <p>Similarly, the <code>Update</code> accounts struct is marked with the <code>#[account(mut)]</code> attribute.
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Marking an account as <code>mut</code> persists any changes made upon exiting the program.</p> <p>Here we've covered the basics of how to interact with accounts. In a later tutorial,
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we'll delve more deeply into deriving <code>Accounts</code>, but for now, just know
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you must mark an account <code>init</code> when using it for the first time and <code>mut</code>
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for persisting changes.</p> <h2 id="creating-and-initializing-accounts"><a href="#creating-and-initializing-accounts" class="header-anchor">#</a> Creating and Initializing Accounts</h2> <p>We can interact with the program as follows.</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token comment">// The program to execute.</span>
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<span class="token keyword">const</span> program <span class="token operator">=</span> anchor<span class="token punctuation">.</span>workspace<span class="token punctuation">.</span>Basic1<span class="token punctuation">;</span>
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<span class="token comment">// The Account to create.</span>
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<span class="token keyword">const</span> myAccount <span class="token operator">=</span> anchor<span class="token punctuation">.</span>web3<span class="token punctuation">.</span>Keypair<span class="token punctuation">.</span><span class="token function">generate</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
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<span class="token comment">// Create the new account and initialize it with the program.</span>
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<span class="token keyword">await</span> program<span class="token punctuation">.</span>rpc<span class="token punctuation">.</span><span class="token function">initialize</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">anchor<span class="token punctuation">.</span>BN</span><span class="token punctuation">(</span><span class="token number">1234</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
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accounts<span class="token operator">:</span> <span class="token punctuation">{</span>
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myAccount<span class="token operator">:</span> myAccount<span class="token punctuation">.</span>publicKey<span class="token punctuation">,</span>
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user<span class="token operator">:</span> provider<span class="token punctuation">.</span>wallet<span class="token punctuation">.</span>publicKey<span class="token punctuation">,</span>
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systemProgram<span class="token operator">:</span> SystemProgram<span class="token punctuation">.</span>programId<span class="token punctuation">,</span>
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<span class="token punctuation">}</span><span class="token punctuation">,</span>
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signers<span class="token operator">:</span> <span class="token punctuation">[</span>myAccount<span class="token punctuation">]</span><span class="token punctuation">,</span>
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<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre></div><p>The last element passed into the method is common amongst all dynamically generated
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methods on the <code>rpc</code> namespace, containing several options for a transaction. Here,
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we specify the <code>accounts</code> field, an object of all the addresses the transaction
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needs to touch, and the <code>signers</code> array of all <code>Signer</code> objects needed to sign the
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transaction. Because <code>myAccount</code> is being created, the Solana runtime requires it
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to sign the transaction.</p> <details class="custom-block details"><summary>DETAILS</summary> <p>If you've developed on Solana before, you might notice two things 1) the ordering of the accounts doesn't
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matter and 2) the <code>isWritable</code> and <code>isSigner</code>
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options are not specified on the account anywhere. In both cases, the framework takes care
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of these details for you, by reading the IDL.</p></details> <p>As before, we can run the example tests.</p> <div class="language- extra-class"><pre class="language-text"><code>anchor test
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</code></pre></div><h2 id="next-steps"><a href="#next-steps" class="header-anchor">#</a> Next Steps</h2> <p>We've covered all the basics of developing applications using Anchor. However, we've
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left out one important aspect to ensure the security of our programs--validating input
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and access control. We'll cover that next.</p></div> <footer class="page-edit"><!----> <!----></footer> <div class="page-nav"><p class="inner"><span class="prev">
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