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<h1 class='fqn'><span class='in-band'>Function <a href='../index.html'>std</a>::<wbr><a href='index.html'>slice</a>::<wbr><a class="fn" href=''>from_raw_parts</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'>
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</span><a class='srclink' href='../../src/core/slice/mod.rs.html#2692-2694' title='goto source code'>[src]</a></span></h1>
<div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="primitive" href="../primitive.slice.html">&'a [</a><a class="primitive" href="../primitive.u8.html">u8</a><a class="primitive" href="../primitive.slice.html">]</a></span></div><div class="content hidden"><h3 class="important">Important traits for <a class="primitive" href="../primitive.slice.html">&'a [</a><a class="primitive" href="../primitive.u8.html">u8</a><a class="primitive" href="../primitive.slice.html">]</a></h3><code class="content"><span class="where fmt-newline">impl<'a> <a class="trait" href="../../std/io/trait.Read.html" title="trait std::io::Read">Read</a> for <a class="primitive" href="../primitive.slice.html">&'a [</a><a class="primitive" href="../primitive.u8.html">u8</a><a class="primitive" href="../primitive.slice.html">]</a></span><span class="where fmt-newline">impl<'a> <a class="trait" href="../../std/io/trait.Write.html" title="trait std::io::Write">Write</a> for <a class="primitive" href="../primitive.slice.html">&'a mut [</a><a class="primitive" href="../primitive.u8.html">u8</a><a class="primitive" href="../primitive.slice.html">]</a></span></code></div></div><pre class='rust fn'>pub unsafe fn from_raw_parts<'a, T>(p: <a class="primitive" href="../primitive.pointer.html">*const T</a>, len: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="primitive" href="../primitive.slice.html">&'a [T]</a></pre><div class='docblock'><p>Forms a slice from a pointer and a length.</p>
<p>The <code>len</code> argument is the number of <strong>elements</strong>, not the number of bytes.</p>
<h1 id="safety" class="section-header"><a href="#safety">Safety</a></h1>
<p>This function is unsafe as there is no guarantee that the given pointer is
valid for <code>len</code> elements, nor whether the lifetime inferred is a suitable
lifetime for the returned slice.</p>
<p><code>p</code> must be non-null, even for zero-length slices, because non-zero bits
are required to distinguish between a zero-length slice within <code>Some()</code>
from <code>None</code>. <code>p</code> can be a bogus non-dereferencable pointer, such as <code>0x1</code>,
for zero-length slices, though.</p>
<h1 id="caveat" class="section-header"><a href="#caveat">Caveat</a></h1>
<p>The lifetime for the returned slice is inferred from its usage. To
prevent accidental misuse, it's suggested to tie the lifetime to whichever
source lifetime is safe in the context, such as by providing a helper
function taking the lifetime of a host value for the slice, or by explicit
annotation.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">slice</span>;
<span class="comment">// manifest a slice out of thin air!</span>
<span class="kw">let</span> <span class="ident">ptr</span> <span class="op">=</span> <span class="number">0x1234</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="ident">amt</span> <span class="op">=</span> <span class="number">10</span>;
<span class="kw">unsafe</span> {
<span class="kw">let</span> <span class="ident">slice</span> <span class="op">=</span> <span class="ident">slice</span>::<span class="ident">from_raw_parts</span>(<span class="ident">ptr</span>, <span class="ident">amt</span>);
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Ause%20std%3A%3Aslice%3B%0A%0A%2F%2F%20manifest%20a%20slice%20out%20of%20thin%20air!%0Alet%20ptr%20%3D%200x1234%20as%20*const%20usize%3B%0Alet%20amt%20%3D%2010%3B%0Aunsafe%20%7B%0A%20%20%20%20let%20slice%20%3D%20slice%3A%3Afrom_raw_parts(ptr%2C%20amt)%3B%0A%7D%0A%7D">Run</a></pre>
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