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push_front [C++ Reference]
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<h2><a name="push_front" id="push_front">push_front</a></h2>
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<p>
Syntax:
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<pre class="c code c++" style="font-family:monospace;"> <span class="co2">#include <deque></span>
<span class="kw4">void</span> push_front<span class="br0">(</span> <span class="kw4">const</span> TYPE<span class="sy0">&</span> val <span class="br0">)</span><span class="sy0">;</span></pre>
<p>
The push_front function inserts <code>val</code> at the beginning of the deque.
</p>
<p>
push_front runs in <a href="../../complexity.html" class="wikilink1" title="complexity">constant time</a>.
</p>
<p>
For example, the following code uses push_front to insert several doubles into a deque, and then uses the <a href="../../stl/algorithm/copy.html" class="wikilink1" title="stl:algorithm:copy">copy algorithm</a> to display the deque:
</p>
<pre class="c code c++" style="font-family:monospace;"> deque<span class="sy0"><</span>double<span class="sy0">></span> values<span class="sy0">;</span>
ostream_iterator<span class="sy0"><</span>double<span class="sy0">></span> output<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> <span class="st0">" "</span> <span class="br0">)</span><span class="sy0">;</span>
values.<span class="me1">push_front</span><span class="br0">(</span> 2.2 <span class="br0">)</span><span class="sy0">;</span>
values.<span class="me1">push_front</span><span class="br0">(</span> 3.5 <span class="br0">)</span><span class="sy0">;</span>
values.<span class="me1">push_back</span><span class="br0">(</span> 1.1 <span class="br0">)</span><span class="sy0">;</span>
<span class="kw1">for</span><span class="br0">(</span> size_t i <span class="sy0">=</span> <span class="nu0">0</span><span class="sy0">;</span> i <span class="sy0"><</span> values.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> <span class="sy0">++</span>i <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> values<span class="br0">[</span>i<span class="br0">]</span> <span class="sy0"><<</span> <span class="st0">' '</span><span class="sy0">;</span>
values.<span class="me1">pop_front</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> <span class="co1">// remove first element</span>
copy<span class="br0">(</span> values.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">,</span> values.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">,</span> output <span class="br0">)</span><span class="sy0">;</span>
values<span class="br0">[</span>1<span class="br0">]</span> <span class="sy0">=</span> <span class="nu16">5.4</span><span class="sy0">;</span>
copy<span class="br0">(</span> values.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">,</span> values.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">,</span> output <span class="br0">)</span><span class="sy0">;</span>
<p>
Related Topics: <a href="../../stl/deque/assign.html" class="wikilink1" title="stl:deque:assign">assign</a>, <a href="../../stl/deque/front.html" class="wikilink1" title="stl:deque:front">front</a>, <a href="../../stl/deque/insert.html" class="wikilink1" title="stl:deque:insert">insert</a>, <a href="../../stl/deque/pop_front.html" class="wikilink1" title="stl:deque:pop_front">pop_front</a>, <a href="../../stl/deque/push_back.html" class="wikilink1" title="stl:deque:push_back">push_back</a>
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