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<h1 class='fqn'><span class='in-band'>Function <a href='../index.html'>std</a>::<wbr><a href='index.html'>intrinsics</a>::<wbr><a class="fn" href=''>copy</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/intrinsics.rs.html#1033' title='goto source code'>[src]</a></span></h1>
<pre class='rust fn'>pub unsafe extern "rust-intrinsic" fn copy<T>(<br> src: <a class="primitive" href="../primitive.pointer.html">*const T</a>, <br> dst: <a class="primitive" href="../primitive.pointer.html">*mut T</a>, <br> count: <a class="primitive" href="../primitive.usize.html">usize</a><br>)</pre><div class='docblock'><p>Copies <code>count * size_of<T></code> bytes from <code>src</code> to <code>dst</code>. The source
and destination may overlap.</p>
<p><code>copy</code> is semantically equivalent to C's <code>memmove</code>.</p>
<h1 id="safety" class="section-header"><a href="#safety">Safety</a></h1>
<p>Care must be taken with the ownership of <code>src</code> and <code>dst</code>.
This method semantically moves the values of <code>src</code> into <code>dst</code>.
However it does not drop the contents of <code>dst</code>, or prevent the contents of <code>src</code>
from being dropped or used.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<p>Efficiently create a Rust vector from an unsafe buffer:</p>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">ptr</span>;
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">from_buf_raw</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">ptr</span>: <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">T</span>, <span class="ident">elts</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="ident">Vec</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">dst</span> <span class="op">=</span> <span class="ident">Vec</span>::<span class="ident">with_capacity</span>(<span class="ident">elts</span>);
<span class="ident">dst</span>.<span class="ident">set_len</span>(<span class="ident">elts</span>);
<span class="ident">ptr</span>::<span class="ident">copy</span>(<span class="ident">ptr</span>, <span class="ident">dst</span>.<span class="ident">as_mut_ptr</span>(), <span class="ident">elts</span>);
<span class="ident">dst</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%3Aptr%3B%0A%0A%23%5Ballow(dead_code)%5D%0Aunsafe%20fn%20from_buf_raw%3CT%3E(ptr%3A%20*const%20T%2C%20elts%3A%20usize)%20-%3E%20Vec%3CT%3E%20%7B%0A%20%20%20%20let%20mut%20dst%20%3D%20Vec%3A%3Awith_capacity(elts)%3B%0A%20%20%20%20dst.set_len(elts)%3B%0A%20%20%20%20ptr%3A%3Acopy(ptr%2C%20dst.as_mut_ptr()%2C%20elts)%3B%0A%20%20%20%20dst%0A%7D%0A%7D">Run</a></pre>
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