<!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"><meta name="description" content="API documentation for the Rust `LineWriter` struct in crate `std`."><meta name="keywords" content="rust, rustlang, rust-lang, LineWriter"><title>std::io::LineWriter - Rust</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script src="../../storage.js"></script><link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"></head><body class="rustdoc struct"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../std/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a><p class='location'>Struct LineWriter</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#methods">Methods</a><div class="sidebar-links"><a href="#method.new">new</a><a href="#method.with_capacity">with_capacity</a><a href="#method.get_ref">get_ref</a><a href="#method.get_mut">get_mut</a><a href="#method.into_inner">into_inner</a></div><a class="sidebar-title" href="#implementations">Trait Implementations</a><div class="sidebar-links"><a href="#impl-Write">Write</a><a href="#impl-Debug">Debug</a></div><a class="sidebar-title" href="#synthetic-implementations">Auto Trait Implementations</a><div class="sidebar-links"><a href="#impl-Send">Send</a><a href="#impl-Sync">Sync</a></div></div><p class='location'><a href='../index.html'>std</a>::<wbr><a href='index.html'>io</a></p><script>window.sidebarCurrent = {name: 'LineWriter', ty: 'struct', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='in-band'>Struct <a href='../index.html'>std</a>::<wbr><a href='index.html'>io</a>::<wbr><a class="struct" href=''>LineWriter</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='../../src/std/io/buffered.rs.html#770-773' title='goto source code'>[src]</a></span></h1><div class="docblock type-decl"><pre class='rust struct'>pub struct LineWriter<W: <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a>> { /* fields omitted */ }</pre></div><div class='docblock'><p>Wraps a writer and buffers output to it, flushing whenever a newline
(<code>0x0a</code>, <code>'\n'</code>) is detected.</p>
<p>The <a href="struct.BufWriter.html"><code>BufWriter</code></a> struct wraps a writer and buffers its output.
But it only does this batched write when it goes out of scope, or when the
internal buffer is full. Sometimes, you'd prefer to write each line as it's
completed, rather than the entire buffer at once. Enter <code>LineWriter</code>. It
does exactly that.</p>
<p>Like <a href="../../std/io/struct.BufWriter.html" title="`BufWriter`"><code>BufWriter</code></a>, a <code>LineWriter</code>’s buffer will also be flushed when the
<code>LineWriter</code> goes out of scope or when its internal buffer is full.</p>
<p>If there's still a partial line in the buffer when the <code>LineWriter</code> is
dropped, it will flush those contents.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<p>We can use <code>LineWriter</code> to write one line at a time, significantly
reducing the number of actual writes to the file.</p>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fs</span>::<span class="ident">File</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="ident">prelude</span>::<span class="kw-2">*</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="ident">LineWriter</span>;
<span class="kw">fn</span> <span class="ident">main</span>() <span class="op">-></span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="kw">let</span> <span class="ident">road_not_taken</span> <span class="op">=</span> <span class="string">b"I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I -
I took the one less traveled by,
And that has made all the difference."</span>;
<span class="kw">let</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">File</span>::<span class="ident">create</span>(<span class="string">"poem.txt"</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">LineWriter</span>::<span class="ident">new</span>(<span class="ident">file</span>);
<span class="kw">for</span> <span class="kw-2">&</span><span class="ident">byte</span> <span class="kw">in</span> <span class="ident">road_not_taken</span>.<span class="ident">iter</span>() {
<span class="ident">file</span>.<span class="ident">write</span>(<span class="kw-2">&</span>[<span class="ident">byte</span>]).<span class="ident">unwrap</span>();
}
<span class="comment">// let's check we did the right thing.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">File</span>::<span class="ident">open</span>(<span class="string">"poem.txt"</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">contents</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">new</span>();
<span class="ident">file</span>.<span class="ident">read_to_string</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">contents</span>)<span class="question-mark">?</span>;
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">contents</span>.<span class="ident">as_bytes</span>(), <span class="kw-2">&</span><span class="ident">road_not_taken</span>[..]);
<span class="prelude-val">Ok</span>(())
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Ause%20std%3A%3Afs%3A%3AFile%3B%0Ause%20std%3A%3Aio%3A%3Aprelude%3A%3A*%3B%0Ause%20std%3A%3Aio%3A%3ALineWriter%3B%0A%0Afn%20main()%20-%3E%20std%3A%3Aio%3A%3AResult%3C()%3E%20%7B%0A%20%20%20%20let%20road_not_taken%20%3D%20b%22I%20shall%20be%20telling%20this%20with%20a%20sigh%0ASomewhere%20ages%20and%20ages%20hence%3A%0ATwo%20roads%20diverged%20in%20a%20wood%2C%20and%20I%20-%0AI%20took%20the%20one%20less%20traveled%20by%2C%0AAnd%20that%20has%20made%20all%20the%20difference.%22%3B%0A%0A%20%20%20%20let%20file%20%3D%20File%3A%3Acreate(%22poem.txt%22)%3F%3B%0A%20%20%20%20let%20mut%20file%20%3D%20LineWriter%3A%3Anew(file)%3B%0A%0A%20%20%20%20for%20%26byte%20in%20road_not_taken.iter()%20%7B%0A%20%20%20%20%20%20%20file.write(%26%5Bbyte%5D).unwrap()%3B%0A%20%20%20%20%7D%0A%0A%20%20%20%20%2F%2F%20let's%20check%20we%20did%20the%20right%20thing.%0A%20%20%20%20let%20mut%20file%20%3D%20File%3A%3Aopen(%22poem.txt%22)%3F%3B%0A%20%20%20%20let%20mut%20contents%20%3D%20String%3A%3Anew()%3B%0A%0A%20%20%20%20file.read_to_string(%26mut%20contents)%3F%3B%0A%0A%20%20%20%20assert_eq!(contents.as_bytes()%2C%20%26road_not_taken%5B..%5D)%3B%0A%20%20%20%20Ok(())%0A%7D">Run</a></pre>
</div>
<h2 id='methods' class='small-section-header'>
Methods<a href='#methods' class='anchor'></a>
</h2>
<h3 id='impl' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl<W: <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a>> <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></code><a href='#impl' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#775-893' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.new' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></h3><code class="content"><span class="where fmt-newline">impl<W: <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a>> <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></span></code></div></div><span id='new.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.new' class='fnname'>new</a>(inner: W) -> <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#791-794' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Creates a new <code>LineWriter</code>.</p>
<h1 id="examples-1" class="section-header"><a href="#examples-1">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fs</span>::<span class="ident">File</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="ident">LineWriter</span>;
<span class="kw">fn</span> <span class="ident">main</span>() <span class="op">-></span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="kw">let</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">File</span>::<span class="ident">create</span>(<span class="string">"poem.txt"</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">LineWriter</span>::<span class="ident">new</span>(<span class="ident">file</span>);
<span class="prelude-val">Ok</span>(())
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Ause%20std%3A%3Afs%3A%3AFile%3B%0Ause%20std%3A%3Aio%3A%3ALineWriter%3B%0A%0Afn%20main()%20-%3E%20std%3A%3Aio%3A%3AResult%3C()%3E%20%7B%0A%20%20%20%20let%20file%20%3D%20File%3A%3Acreate(%22poem.txt%22)%3F%3B%0A%20%20%20%20let%20file%20%3D%20LineWriter%3A%3Anew(file)%3B%0A%20%20%20%20Ok(())%0A%7D">Run</a></pre>
</div><h4 id='method.with_capacity' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></h3><code class="content"><span class="where fmt-newline">impl<W: <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a>> <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></span></code></div></div><span id='with_capacity.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.with_capacity' class='fnname'>with_capacity</a>(cap: <a class="primitive" href="../primitive.usize.html">usize</a>, inner: W) -> <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#812-817' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Creates a new <code>LineWriter</code> with a specified capacity for the internal
buffer.</p>
<h1 id="examples-2" class="section-header"><a href="#examples-2">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fs</span>::<span class="ident">File</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="ident">LineWriter</span>;
<span class="kw">fn</span> <span class="ident">main</span>() <span class="op">-></span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="kw">let</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">File</span>::<span class="ident">create</span>(<span class="string">"poem.txt"</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">LineWriter</span>::<span class="ident">with_capacity</span>(<span class="number">100</span>, <span class="ident">file</span>);
<span class="prelude-val">Ok</span>(())
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Ause%20std%3A%3Afs%3A%3AFile%3B%0Ause%20std%3A%3Aio%3A%3ALineWriter%3B%0A%0Afn%20main()%20-%3E%20std%3A%3Aio%3A%3AResult%3C()%3E%20%7B%0A%20%20%20%20let%20file%20%3D%20File%3A%3Acreate(%22poem.txt%22)%3F%3B%0A%20%20%20%20let%20file%20%3D%20LineWriter%3A%3Awith_capacity(100%2C%20file)%3B%0A%20%20%20%20Ok(())%0A%7D">Run</a></pre>
</div><h4 id='method.get_ref' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="primitive" href="../primitive.reference.html">&'a mut </a>I</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="primitive" href="../primitive.reference.html">&'a mut </a>I</h3><code class="content"><span class="where fmt-newline">impl<'a, I> <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a> for <a class="primitive" href="../primitive.reference.html">&'a mut </a>I <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>, </span></span><span class="where fmt-newline"> type <a href='../../std/iter/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = <I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="type" href="../../std/iter/trait.Iterator.html#associatedtype.Item" title="type std::iter::Iterator::Item">Item</a>;</span><span class="where fmt-newline">impl<'a, R: <a class="trait" href="../../std/io/trait.Read.html" title="trait std::io::Read">Read</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>> <a class="trait" href="../../std/io/trait.Read.html" title="trait std::io::Read">Read</a> for <a class="primitive" href="../primitive.reference.html">&'a mut </a>R</span><span class="where fmt-newline">impl<'a, W: <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>> <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> for <a class="primitive" href="../primitive.reference.html">&'a mut </a>W</span></code></div></div><span id='get_ref.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.get_ref' class='fnname'>get_ref</a>(&self) -> <a class="primitive" href="../primitive.reference.html">&</a>W</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#836' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Gets a reference to the underlying writer.</p>
<h1 id="examples-3" class="section-header"><a href="#examples-3">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fs</span>::<span class="ident">File</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="ident">LineWriter</span>;
<span class="kw">fn</span> <span class="ident">main</span>() <span class="op">-></span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="kw">let</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">File</span>::<span class="ident">create</span>(<span class="string">"poem.txt"</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">LineWriter</span>::<span class="ident">new</span>(<span class="ident">file</span>);
<span class="kw">let</span> <span class="ident">reference</span> <span class="op">=</span> <span class="ident">file</span>.<span class="ident">get_ref</span>();
<span class="prelude-val">Ok</span>(())
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Ause%20std%3A%3Afs%3A%3AFile%3B%0Ause%20std%3A%3Aio%3A%3ALineWriter%3B%0A%0Afn%20main()%20-%3E%20std%3A%3Aio%3A%3AResult%3C()%3E%20%7B%0A%20%20%20%20let%20file%20%3D%20File%3A%3Acreate(%22poem.txt%22)%3F%3B%0A%20%20%20%20let%20file%20%3D%20LineWriter%3A%3Anew(file)%3B%0A%0A%20%20%20%20let%20reference%20%3D%20file.get_ref()%3B%0A%20%20%20%20Ok(())%0A%7D">Run</a></pre>
</div><h4 id='method.get_mut' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="primitive" href="../primitive.reference.html">&'a mut </a>I</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="primitive" href="../primitive.reference.html">&'a mut </a>I</h3><code class="content"><span class="where fmt-newline">impl<'a, I> <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a> for <a class="primitive" href="../primitive.reference.html">&'a mut </a>I <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>, </span></span><span class="where fmt-newline"> type <a href='../../std/iter/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = <I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="type" href="../../std/iter/trait.Iterator.html#associatedtype.Item" title="type std::iter::Iterator::Item">Item</a>;</span><span class="where fmt-newline">impl<'a, R: <a class="trait" href="../../std/io/trait.Read.html" title="trait std::io::Read">Read</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>> <a class="trait" href="../../std/io/trait.Read.html" title="trait std::io::Read">Read</a> for <a class="primitive" href="../primitive.reference.html">&'a mut </a>R</span><span class="where fmt-newline">impl<'a, W: <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>> <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> for <a class="primitive" href="../primitive.reference.html">&'a mut </a>W</span></code></div></div><span id='get_mut.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.get_mut' class='fnname'>get_mut</a>(&mut self) -> <a class="primitive" href="../primitive.reference.html">&mut </a>W</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#859' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Gets a mutable reference to the underlying writer.</p>
<p>Caution must be taken when calling methods on the mutable reference
returned as extra writes could corrupt the output stream.</p>
<h1 id="examples-4" class="section-header"><a href="#examples-4">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fs</span>::<span class="ident">File</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="ident">LineWriter</span>;
<span class="kw">fn</span> <span class="ident">main</span>() <span class="op">-></span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="kw">let</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">File</span>::<span class="ident">create</span>(<span class="string">"poem.txt"</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">LineWriter</span>::<span class="ident">new</span>(<span class="ident">file</span>);
<span class="comment">// we can use reference just like file</span>
<span class="kw">let</span> <span class="ident">reference</span> <span class="op">=</span> <span class="ident">file</span>.<span class="ident">get_mut</span>();
<span class="prelude-val">Ok</span>(())
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Ause%20std%3A%3Afs%3A%3AFile%3B%0Ause%20std%3A%3Aio%3A%3ALineWriter%3B%0A%0Afn%20main()%20-%3E%20std%3A%3Aio%3A%3AResult%3C()%3E%20%7B%0A%20%20%20%20let%20file%20%3D%20File%3A%3Acreate(%22poem.txt%22)%3F%3B%0A%20%20%20%20let%20mut%20file%20%3D%20LineWriter%3A%3Anew(file)%3B%0A%0A%20%20%20%20%2F%2F%20we%20can%20use%20reference%20just%20like%20file%0A%20%20%20%20let%20reference%20%3D%20file.get_mut()%3B%0A%20%20%20%20Ok(())%0A%7D">Run</a></pre>
</div><h4 id='method.into_inner' class="method"><span id='into_inner.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.into_inner' class='fnname'>into_inner</a>(self) -> <a class="enum" href="../../std/result/enum.Result.html" title="enum std::result::Result">Result</a><W, <a class="struct" href="../../std/io/struct.IntoInnerError.html" title="struct std::io::IntoInnerError">IntoInnerError</a><<a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W>>></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#885-892' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Unwraps this <code>LineWriter</code>, returning the underlying writer.</p>
<p>The internal buffer is written out before returning the writer.</p>
<p>An <code>Err</code> will be returned if an error occurs while flushing the buffer.</p>
<h1 id="examples-5" class="section-header"><a href="#examples-5">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fs</span>::<span class="ident">File</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="ident">LineWriter</span>;
<span class="kw">fn</span> <span class="ident">main</span>() <span class="op">-></span> <span class="ident">std</span>::<span class="ident">io</span>::<span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="kw">let</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">File</span>::<span class="ident">create</span>(<span class="string">"poem.txt"</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">writer</span>: <span class="ident">LineWriter</span><span class="op"><</span><span class="ident">File</span><span class="op">></span> <span class="op">=</span> <span class="ident">LineWriter</span>::<span class="ident">new</span>(<span class="ident">file</span>);
<span class="kw">let</span> <span class="ident">file</span>: <span class="ident">File</span> <span class="op">=</span> <span class="ident">writer</span>.<span class="ident">into_inner</span>()<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>(())
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Ause%20std%3A%3Afs%3A%3AFile%3B%0Ause%20std%3A%3Aio%3A%3ALineWriter%3B%0A%0Afn%20main()%20-%3E%20std%3A%3Aio%3A%3AResult%3C()%3E%20%7B%0A%20%20%20%20let%20file%20%3D%20File%3A%3Acreate(%22poem.txt%22)%3F%3B%0A%0A%20%20%20%20let%20writer%3A%20LineWriter%3CFile%3E%20%3D%20LineWriter%3A%3Anew(file)%3B%0A%0A%20%20%20%20let%20file%3A%20File%20%3D%20writer.into_inner()%3F%3B%0A%20%20%20%20Ok(())%0A%7D">Run</a></pre>
</div></div>
<h2 id='implementations' class='small-section-header'>
Trait Implementations<a href='#implementations' class='anchor'></a>
</h2>
<div id='implementations-list'><h3 id='impl-Write' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl<W: <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a>> <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W></code><a href='#impl-Write' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#896-938' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.write' class="method"><span id='write.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/io/trait.Write.html#tymethod.write' class='fnname'>write</a>(&mut self, buf: <a class="primitive" href="../primitive.slice.html">&[</a><a class="primitive" href="../primitive.u8.html">u8</a><a class="primitive" href="../primitive.slice.html">]</a>) -> <a class="type" href="../../std/io/type.Result.html" title="type std::io::Result">Result</a><<a class="primitive" href="../primitive.usize.html">usize</a>></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#897-931' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Write a buffer into this object, returning how many bytes were written. <a href="../../std/io/trait.Write.html#tymethod.write">Read more</a></p>
</div><h4 id='method.flush' class="method"><span id='flush.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/io/trait.Write.html#tymethod.flush' class='fnname'>flush</a>(&mut self) -> <a class="type" href="../../std/io/type.Result.html" title="type std::io::Result">Result</a><<a class="primitive" href="../primitive.unit.html">()</a>></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#933-937' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Flush this output stream, ensuring that all intermediately buffered contents reach their destination. <a href="../../std/io/trait.Write.html#tymethod.flush">Read more</a></p>
</div><h4 id='method.write_all' class="method"><span id='write_all.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/io/trait.Write.html#method.write_all' class='fnname'>write_all</a>(&mut self, buf: <a class="primitive" href="../primitive.slice.html">&[</a><a class="primitive" href="../primitive.u8.html">u8</a><a class="primitive" href="../primitive.slice.html">]</a>) -> <a class="type" href="../../std/io/type.Result.html" title="type std::io::Result">Result</a><<a class="primitive" href="../primitive.unit.html">()</a>></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/mod.rs.html#1109-1120' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Attempts to write an entire buffer into this write. <a href="../../std/io/trait.Write.html#method.write_all">Read more</a></p>
</div><h4 id='method.write_fmt' class="method"><span id='write_fmt.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/io/trait.Write.html#method.write_fmt' class='fnname'>write_fmt</a>(&mut self, fmt: <a class="struct" href="../../std/fmt/struct.Arguments.html" title="struct std::fmt::Arguments">Arguments</a>) -> <a class="type" href="../../std/io/type.Result.html" title="type std::io::Result">Result</a><<a class="primitive" href="../primitive.unit.html">()</a>></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/mod.rs.html#1161-1193' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Writes a formatted string into this writer, returning any error encountered. <a href="../../std/io/trait.Write.html#method.write_fmt">Read more</a></p>
</div><h4 id='method.by_ref' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="primitive" href="../primitive.reference.html">&'a mut </a>I</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="primitive" href="../primitive.reference.html">&'a mut </a>I</h3><code class="content"><span class="where fmt-newline">impl<'a, I> <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a> for <a class="primitive" href="../primitive.reference.html">&'a mut </a>I <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>, </span></span><span class="where fmt-newline"> type <a href='../../std/iter/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = <I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="type" href="../../std/iter/trait.Iterator.html#associatedtype.Item" title="type std::iter::Iterator::Item">Item</a>;</span><span class="where fmt-newline">impl<'a, R: <a class="trait" href="../../std/io/trait.Read.html" title="trait std::io::Read">Read</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>> <a class="trait" href="../../std/io/trait.Read.html" title="trait std::io::Read">Read</a> for <a class="primitive" href="../primitive.reference.html">&'a mut </a>R</span><span class="where fmt-newline">impl<'a, W: <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>> <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> for <a class="primitive" href="../primitive.reference.html">&'a mut </a>W</span></code></div></div><span id='by_ref.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/io/trait.Write.html#method.by_ref' class='fnname'>by_ref</a>(&mut self) -> <a class="primitive" href="../primitive.reference.html">&mut </a>Self <span class="where fmt-newline">where<br> Self: <a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>, </span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/mod.rs.html#1217' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Creates a "by reference" adaptor for this instance of <code>Write</code>. <a href="../../std/io/trait.Write.html#method.by_ref">Read more</a></p>
</div></div><h3 id='impl-Debug' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl<W: <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a>> <a class="trait" href="../../std/fmt/trait.Debug.html" title="trait std::fmt::Debug">Debug</a> for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W> <span class="where fmt-newline">where<br> W: <a class="trait" href="../../std/fmt/trait.Debug.html" title="trait std::fmt::Debug">Debug</a>, </span></code><a href='#impl-Debug' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#941-949' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&self, fmt: &mut <a class="struct" href="../../std/fmt/struct.Formatter.html" title="struct std::fmt::Formatter">Formatter</a>) -> <a class="type" href="../../std/fmt/type.Result.html" title="type std::fmt::Result">Result</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/io/buffered.rs.html#942-948' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Formats the value using the given formatter. <a href="../../std/fmt/trait.Debug.html#tymethod.fmt">Read more</a></p>
</div></div></div>
<h2 id='synthetic-implementations' class='small-section-header'>
Auto Trait Implementations<a href='#synthetic-implementations' class='anchor'></a>
</h2>
<div id='synthetic-implementations-list'>
<h3 id='impl-Send' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl<W> <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a> for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W> <span class="where fmt-newline">where<br> W: <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a>, </span></code><a href='#impl-Send' class='anchor'></a></span></td><td><span class='out-of-band'></span></td></tr></tbody></table></h3><div class='impl-items'></div><h3 id='impl-Sync' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl<W> <a class="trait" href="../../std/marker/trait.Sync.html" title="trait std::marker::Sync">Sync</a> for <a class="struct" href="../../std/io/struct.LineWriter.html" title="struct std::io::LineWriter">LineWriter</a><W> <span class="where fmt-newline">where<br> W: <a class="trait" href="../../std/marker/trait.Sync.html" title="trait std::marker::Sync">Sync</a>, </span></code><a href='#impl-Sync' class='anchor'></a></span></td><td><span class='out-of-band'></span></td></tr></tbody></table></h3><div class='impl-items'></div></div></section><section id="search" class="content hidden"></section><section class="footer"></section><aside id="help" class="hidden"><div><h1 class="hidden">Help</h1><div class="shortcuts"><h2>Keyboard Shortcuts</h2><dl><dt><kbd>?</kbd></dt><dd>Show this help dialog</dd><dt><kbd>S</kbd></dt><dd>Focus the search field</dd><dt><kbd>↑</kbd></dt><dd>Move up in search results</dd><dt><kbd>↓</kbd></dt><dd>Move down in search results</dd><dt><kbd>↹</kbd></dt><dd>Switch tab</dd><dt><kbd>⏎</kbd></dt><dd>Go to active search result</dd><dt><kbd>+</kbd></dt><dd>Expand all sections</dd><dt><kbd>-</kbd></dt><dd>Collapse all sections</dd></dl></div><div class="infos"><h2>Search Tricks</h2><p>Prefix searches with a type followed by a colon (e.g. <code>fn:</code>) to restrict the search to a given type.</p><p>Accepted types are: <code>fn</code>, <code>mod</code>, <code>struct</code>, <code>enum</code>, <code>trait</code>, <code>type</code>, <code>macro</code>, and <code>const</code>.</p><p>Search functions by type signature (e.g. <code>vec -> usize</code> or <code>* -> vec</code>)</p><p>Search multiple things at once by splitting your query with comma (e.g. <code>str,u8</code> or <code>String,struct:Vec,test</code>)</p></div></div></aside><script>window.rootPath = "../../";window.currentCrate = "std";</script><script src="../../aliases.js"></script><script src="../../main.js"></script><script defer src="../../search-index.js"></script></body></html>
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