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copy_backward [C++ Reference]
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<h2><a name="copy_backward" id="copy_backward">copy_backward</a></h2>
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<p>
Syntax:
</p>
<pre class="c code c++" style="font-family:monospace;"><span class="co2">#include <algorithm></span>
bidirectional_iterator2 copy_backward<span class="br0">(</span> bidirectional_iterator start<span class="sy0">,</span>
bidirectional_iterator end<span class="sy0">,</span>
bidirectional_iterator2 dest <span class="br0">)</span><span class="sy0">;</span></pre>
<p>
copy_backward is similar to <a href="../../stl/algorithm/copy.html" class="wikilink1" title="stl:algorithm:copy">copy</a>, in that both functions copy
elements from <code>start</code> to <code>end</code> to <code>dest</code>. The copy_backward function, however,
starts depositing elements at <code>dest</code> and then works backwards, such that:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="sy0">*</span><span class="br0">(</span>dest<span class="sy0">-</span><span class="nu0">1</span><span class="br0">)</span> <span class="sy0">==</span> <span class="sy0">*</span><span class="br0">(</span>end<span class="sy0">-</span><span class="nu0">1</span><span class="br0">)</span>
<span class="sy0">*</span><span class="br0">(</span>dest<span class="sy0">-</span><span class="nu0">2</span><span class="br0">)</span> <span class="sy0">==</span> <span class="sy0">*</span><span class="br0">(</span>end<span class="sy0">-</span><span class="nu0">2</span><span class="br0">)</span>
<span class="sy0">*</span><span class="br0">(</span>dest<span class="sy0">-</span><span class="nu0">3</span><span class="br0">)</span> <span class="sy0">==</span> <span class="sy0">*</span><span class="br0">(</span>end<span class="sy0">-</span><span class="nu0">3</span><span class="br0">)</span>
...
<span class="sy0">*</span><span class="br0">(</span>dest<span class="sy0">-</span>N<span class="br0">)</span> <span class="sy0">==</span> <span class="sy0">*</span><span class="br0">(</span>end<span class="sy0">-</span>N<span class="br0">)</span></pre>
<p>
The following code uses copy_backward to copy 10 integers into the end of an
empty vector:
</p>
<pre class="c code c++" style="font-family:monospace;"> vector<span class="sy0"><</span>int<span class="sy0">></span> from_vector<span class="sy0">;</span>
<span class="kw1">for</span><span class="br0">(</span> <span class="kw4">int</span> i <span class="sy0">=</span> <span class="nu0">0</span><span class="sy0">;</span> i <span class="sy0"><</span> <span class="nu0">10</span><span class="sy0">;</span> i<span class="sy0">++</span> <span class="br0">)</span> <span class="br0">{</span>
from_vector.<span class="me1">push_back</span><span class="br0">(</span> i <span class="br0">)</span><span class="sy0">;</span>
<span class="br0">}</span>
vector<span class="sy0"><</span>int<span class="sy0">></span> to_vector<span class="br0">(</span>15<span class="br0">)</span><span class="sy0">;</span>
copy_backward<span class="br0">(</span> from_vector.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">,</span> from_vector.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">,</span> to_vector.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span> <span class="br0">)</span><span class="sy0">;</span>
<a href="http://www.opengroup.org/onlinepubs/009695399/functions/cout.html"><span class="kw3">cout</span></a> <span class="sy0"><<</span> <span class="st0">"to_vector contains: "</span><span class="sy0">;</span>
<span class="kw1">for</span><span class="br0">(</span> <span class="kw4">unsigned</span> <span class="kw4">int</span> i <span class="sy0">=</span> <span class="nu0">0</span><span class="sy0">;</span> i <span class="sy0"><</span> to_vector.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> i<span class="sy0">++</span> <span class="br0">)</span> <span class="br0">{</span>
<a href="http://www.opengroup.org/onlinepubs/009695399/functions/cout.html"><span class="kw3">cout</span></a> <span class="sy0"><<</span> to_vector<span class="br0">[</span>i<span class="br0">]</span> <span class="sy0"><<</span> <span class="st0">" "</span><span class="sy0">;</span>
<span class="br0">}</span>
<a href="http://www.opengroup.org/onlinepubs/009695399/functions/cout.html"><span class="kw3">cout</span></a> <span class="sy0"><<</span> endl<span class="sy0">;</span></pre>
<p>
The above code produces the following output:
</p>
<pre class="code">
to_vector contains: 0 0 0 0 0 0 1 2 3 4 5 6 7 8 9</pre>
<p>
Related Topics: <a href="../../stl/algorithm/copy.html" class="wikilink1" title="stl:algorithm:copy">copy</a>, <a href="../../stl/algorithm/copy_n.html" class="wikilink1" title="stl:algorithm:copy_n">copy_n</a>, <a href="../../stl/algorithm/swap.html" class="wikilink1" title="stl:algorithm:swap">swap</a>
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