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<h2><a name="set_constructors_destructors" id="set_constructors_destructors">Set constructors &amp; destructors</a></h2>
<div class="level2">

<p>
Syntax:
</p>
<pre class="c code c++" style="font-family:monospace;">    <span class="co2">#include &lt;set&gt;</span>
    set<span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">;</span>
    set<span class="br0">&#40;</span> <span class="kw4">const</span> set<span class="sy0">&amp;</span> c <span class="br0">&#41;</span><span class="sy0">;</span>
    set<span class="br0">&#40;</span> input_iterator start<span class="sy0">,</span> input_iterator end <span class="br0">&#41;</span><span class="sy0">;</span>
    set<span class="br0">&#40;</span> input_iterator start<span class="sy0">,</span> input_iterator end<span class="sy0">,</span> <span class="kw4">const</span> key_compare<span class="sy0">&amp;</span> cmp <span class="br0">&#41;</span><span class="sy0">;</span>
    explicit set<span class="br0">&#40;</span> <span class="kw4">const</span> key_compare<span class="sy0">&amp;</span> cmp <span class="br0">&#41;</span><span class="sy0">;</span>
    ~set<span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">;</span></pre>
<p>
Every set has a default constructor, copy constructor, and destructor.
</p>

<p>
The default constructor takes no arguments, creates a new instance of that set,
and runs in <a href="../../complexity.html" class="wikilink1" title="complexity">constant time</a>. The default copy constructor runs in <a href="../../complexity.html" class="wikilink1" title="complexity">linear time</a> and
can be used to create a new set that is a copy of the given set c.
</p>

<p>
The default destructor is called when the set should be destroyed.
</p>

<p>
For example, the following code creates and displays a set of integers:
</p>
<pre class="c code c++" style="font-family:monospace;">  <span class="kw4">const</span> <span class="kw4">int</span> max_nums <span class="sy0">=</span> <span class="nu0">10</span><span class="sy0">;</span>
  <span class="kw4">int</span> nums<span class="br0">&#91;</span>max_nums<span class="br0">&#93;</span> <span class="sy0">=</span> <span class="br0">&#123;</span>3<span class="sy0">,</span>1<span class="sy0">,</span>4<span class="sy0">,</span>1<span class="sy0">,</span>5<span class="sy0">,</span>9<span class="sy0">,</span>2<span class="sy0">,</span>6<span class="sy0">,</span>5<span class="sy0">,</span>8<span class="br0">&#125;</span><span class="sy0">;</span>
&nbsp;
  set<span class="sy0">&lt;</span>int<span class="sy0">&gt;</span> digits<span class="sy0">;</span>
  <span class="kw1">for</span><span class="br0">&#40;</span> <span class="kw4">int</span> i <span class="sy0">=</span> <span class="nu0">0</span><span class="sy0">;</span> i <span class="sy0">&lt;</span> max_nums<span class="sy0">;</span> <span class="sy0">++</span>i <span class="br0">&#41;</span> digits.<span class="me1">insert</span><span class="br0">&#40;</span>nums<span class="br0">&#91;</span>i<span class="br0">&#93;</span><span class="br0">&#41;</span><span class="sy0">;</span>
&nbsp;
  <a href="http://www.opengroup.org/onlinepubs/009695399/functions/cout.html"><span class="kw3">cout</span></a> <span class="sy0">&lt;&lt;</span> <span class="st0">&quot;Unique digits are: &quot;</span><span class="sy0">;</span>
  <span class="kw1">for</span><span class="br0">&#40;</span> set<span class="sy0">&lt;</span>int<span class="sy0">&gt;::</span><span class="me2">const_iterator</span> iter <span class="sy0">=</span> digits.<span class="me1">begin</span><span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">;</span>
       iter <span class="sy0">!=</span> digits.<span class="me1">end</span><span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">;</span>
       <span class="sy0">++</span>iter <span class="br0">&#41;</span> <span class="br0">&#123;</span>
    <a href="http://www.opengroup.org/onlinepubs/009695399/functions/cout.html"><span class="kw3">cout</span></a> <span class="sy0">&lt;&lt;</span> <span class="sy0">*</span>iter <span class="sy0">&lt;&lt;</span> <span class="st0">' '</span><span class="sy0">;</span>
  <span class="br0">&#125;</span>
  <a href="http://www.opengroup.org/onlinepubs/009695399/functions/cout.html"><span class="kw3">cout</span></a> <span class="sy0">&lt;&lt;</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy0">;</span></pre>
<p>
When run, this code displays:
</p>
<pre class="code">
Unique digits are: 1 2 3 4 5 6 8 9</pre>
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