<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta name="generator" content="rustdoc"> <title>FFI</title> <link rel="stylesheet" type="text/css" href="../rust.css"> <link rel="shortcut icon" href="https://www.rust-lang.org/favicon.ico"> </head> <body class="rustdoc"> <!--[if lte IE 8]> <div class="warning"> This old browser is unsupported and will most likely display funky things. </div> <![endif]--> <div id="versioninfo"> <img src="https://www.rust-lang.org/logos/rust-logo-32x32-blk.png" width="32" height="32" alt="Rust logo"><br> <span class="white-sticker"><a href="https://www.rust-lang.org">Rust</a> 1.27.1</span><br> <a href="https://github.com/rust-lang/rust/commit/" class="hash white-sticker"></a> </div> <h1 class="title">FFI</h1> <p><small>There is a new edition of the book and this is an old link.</small></p> <blockquote> <p>Sometimes, your Rust code may need to interact with code written in another language. To do this, Rust has a keyword, <code>extern</code>, that facilitates creating and using a <em>Foreign Function Interface</em> (FFI).</p> </blockquote> <pre class="rust rust-example-rendered"> <span class="kw">extern</span> <span class="string">"C"</span> { <span class="kw">fn</span> <span class="ident">abs</span>(<span class="ident">input</span>: <span class="ident">i32</span>) <span class="op">-></span> <span class="ident">i32</span>; } <span class="kw">fn</span> <span class="ident">main</span>() { <span class="kw">unsafe</span> { <span class="macro">println</span><span class="macro">!</span>(<span class="string">"Absolute value of -3 according to C: {}"</span>, <span class="ident">abs</span>(<span class="op">-</span><span class="number">3</span>)); } }<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Aextern%20%22C%22%20%7B%0A%20%20%20%20fn%20abs(input%3A%20i32)%20-%3E%20i32%3B%0A%7D%0A%0Afn%20main()%20%7B%0A%20%20%20%20unsafe%20%7B%0A%20%20%20%20%20%20%20%20println!(%22Absolute%20value%20of%20-3%20according%20to%20C%3A%20%7B%7D%22%2C%20abs(-3))%3B%0A%20%20%20%20%7D%0A%7D">Run</a></pre> <hr /> <p>Here are the relevant sections in the new and old books:</p> <ul> <li><strong><a href="second-edition/ch19-01-unsafe-rust.html#using-extern-functions-to-call-external-code">In the second edition: Ch 19.01 — Unsafe Rust, section <code>extern</code> functions</a></strong></li> <li><small><a href="first-edition/ffi.html">In the first edition: Ch 4.9 — FFI</a></small></li> </ul> <footer><p> Copyright © 2011 The Rust Project Developers. Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a> or the <a href="https://opensource.org/licenses/MIT">MIT license</a>, at your option. </p><p> This file may not be copied, modified, or distributed except according to those terms. </p></footer> </body> </html>