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begin [C++ Reference]
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<span class="bchead">You are here: </span><a href="../../start.html" title="start">C++ Reference</a> » <a href="../../stl/start.html" title="stl:start">C++ Standard Template Library</a> » <a href="../../stl/set/start.html" title="stl:set:start">C++ Sets</a> » <a href="../../stl/set/begin.html" title="stl:set:begin">begin</a> </div>
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<h2><a name="begin" id="begin">begin</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 <set></span>
iterator begin<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span>
const_iterator begin<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span><span class="sy0">;</span></pre>
<p>
The function begin() returns an iterator to the first element of the set. begin
() should run in <a href="../../complexity.html" class="wikilink1" title="complexity">constant time</a>.
</p>
<p>
For example, the following code uses begin() to initialize an iterator that is
used to enumerate a set:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="co1">// Create a set of characters</span>
set<span class="sy0"><</span>char<span class="sy0">></span> charSet<span class="sy0">;</span>
<span class="kw4">const</span> <span class="kw4">char</span><span class="sy0">*</span> s <span class="sy0">=</span> <span class="st0">"Hello There"</span><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> strlen<span class="br0">(</span>s<span class="br0">)</span><span class="sy0">;</span> i<span class="sy0">++</span> <span class="br0">)</span> <span class="br0">{</span>
charSet.<span class="me1">insert</span><span class="br0">(</span> s<span class="br0">[</span>i<span class="br0">]</span> <span class="br0">)</span><span class="sy0">;</span>
<span class="br0">}</span>
<span class="co1">// Display the set</span>
set<span class="sy0"><</span>char<span class="sy0">>::</span><span class="me2">iterator</span> theIterator<span class="sy0">;</span>
<span class="kw1">for</span><span class="br0">(</span> theIterator <span class="sy0">=</span> charSet.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> theIterator <span class="sy0">!=</span> charSet.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> theIterator<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> <span class="sy0">*</span>theIterator<span class="sy0">;</span>
<span class="br0">}</span>
<span class="co1">// output is " HTehlor"</span></pre>
<p>
Related Topics: <a href="../../stl/set/end.html" class="wikilink1" title="stl:set:end">end</a>, <a href="../../stl/set/rbegin.html" class="wikilink1" title="stl:set:rbegin">rbegin</a>, <a href="../../stl/set/rend.html" class="wikilink1" title="stl:set:rend">rend</a>
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