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<h2><a name="erase" id="erase">erase</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>
    <span class="kw4">void</span> erase<span class="br0">&#40;</span> iterator pos <span class="br0">&#41;</span><span class="sy0">;</span>
    <span class="kw4">void</span> erase<span class="br0">&#40;</span> iterator start<span class="sy0">,</span> iterator end <span class="br0">&#41;</span><span class="sy0">;</span>
    size_type erase<span class="br0">&#40;</span> <span class="kw4">const</span> key_type<span class="sy0">&amp;</span> key <span class="br0">&#41;</span><span class="sy0">;</span> <span class="co1">// returns number of erased elements</span></pre>
<p>
The erase function() either erases the element at pos, erases the elements
between start and end, or erases all elements that have the value of key.
</p>

<p>
<strong>With all container types you have to be careful when inserting or erasing elements, since it may lead to invalid iterators.</strong>
</p>

<p>
Especially, set::erase() only invalidates the iterators (and pointers) referencing the element to be erased.
</p>

<p>
The example erases some elements depending on a condition (it will erase the letters B and D):

</p>
<pre class="c code c++" style="font-family:monospace;"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;set&gt;</span>
<span class="co2">#include &lt;iterator&gt;</span>
&nbsp;
using namespace std<span class="sy0">;</span>
&nbsp;
<span class="kw4">int</span> main<span class="br0">&#40;</span><span class="br0">&#41;</span>
<span class="br0">&#123;</span>
    <span class="co1">// Create a set, load it with the first ten characters of the alphabet</span>
    set<span class="sy0">&lt;</span>char<span class="sy0">&gt;</span> alphas<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> <span class="nu0">10</span><span class="sy0">;</span> i<span class="sy0">++</span> <span class="br0">&#41;</span>
    <span class="br0">&#123;</span>
      <span class="kw4">static</span> <span class="kw4">const</span> <span class="kw4">char</span> letters<span class="br0">&#91;</span><span class="br0">&#93;</span> <span class="sy0">=</span> <span class="st0">&quot;ABCDEFGHIJ&quot;</span><span class="sy0">;</span>
      alphas.<span class="me1">insert</span><span class="br0">&#40;</span> alphas.<span class="me1">end</span><span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">,</span> letters<span class="br0">&#91;</span>i<span class="br0">&#93;</span> <span class="br0">&#41;</span><span class="sy0">;</span>
    <span class="br0">&#125;</span>
&nbsp;
    <span class="co1">// display content before</span>
    copy<span class="br0">&#40;</span>alphas.<span class="me1">begin</span><span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">,</span> alphas.<span class="me1">end</span><span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">,</span> ostream_iterator<span class="sy0">&lt;</span>char<span class="sy0">&gt;</span><span class="br0">&#40;</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">&quot;&quot;</span><span class="br0">&#41;</span><span class="br0">&#41;</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">&lt;&lt;</span> endl<span class="sy0">;</span>
&nbsp;
    set<span class="sy0">&lt;</span>char<span class="sy0">&gt;::</span><span class="me2">iterator</span> iter <span class="sy0">=</span> alphas.<span class="me1">begin</span><span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">;</span>
    <span class="kw1">while</span><span class="br0">&#40;</span> iter <span class="sy0">!=</span> alphas.<span class="me1">end</span><span class="br0">&#40;</span><span class="br0">&#41;</span> <span class="br0">&#41;</span>
    <span class="br0">&#123;</span>
      <span class="kw1">if</span> <span class="br0">&#40;</span><span class="sy0">*</span>iter <span class="sy0">==</span> <span class="st0">'B'</span> <span class="sy0">||</span> <span class="sy0">*</span>iter <span class="sy0">==</span> <span class="st0">'D'</span><span class="br0">&#41;</span>
        <span class="co1">// Since post-increment is used, erase() gets a temporary object and</span>
        <span class="co1">// iter has moved beyond the item being erased so it remains valid.</span>
        alphas.<span class="me1">erase</span><span class="br0">&#40;</span> iter<span class="sy0">++</span> <span class="br0">&#41;</span><span class="sy0">;</span>
      <span class="kw1">else</span>
        <span class="sy0">++</span>iter<span class="sy0">;</span>
    <span class="br0">&#125;</span>
&nbsp;
    <span class="co1">// display content after</span>
    copy<span class="br0">&#40;</span>alphas.<span class="me1">begin</span><span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">,</span> alphas.<span class="me1">end</span><span class="br0">&#40;</span><span class="br0">&#41;</span><span class="sy0">,</span> ostream_iterator<span class="sy0">&lt;</span>char<span class="sy0">&gt;</span><span class="br0">&#40;</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">&quot;&quot;</span><span class="br0">&#41;</span><span class="br0">&#41;</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">&lt;&lt;</span> endl<span class="sy0">;</span>
<span class="br0">&#125;</span></pre>
<p>
When run, the above code displays:

</p>
<pre class="code">
ABCDEFGHIJ
ACEFGHIJ</pre>
<p>
Related Topics: <a href="../../stl/set/clear.html" class="wikilink1" title="stl:set:clear">clear</a>
</p>

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