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for_each [C++ Reference]
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<h2><a name="for_each" id="for_each">for_each</a></h2>
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<p>
Syntax:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="co2">#include &lt;algorithm&gt;</span>
UnaryFunction for_each<span class="br0">&#40;</span> input_iterator start<span class="sy0">,</span> input_iterator end<span class="sy0">,</span> UnaryFunction f <span class="br0">&#41;</span><span class="sy0">;</span></pre>
<p>
The for_each() algorithm applies the function f to each of the elements between
start and end. The return value of for_each() is f.
</p>
<p>
For example, the following code snippets define a unary function then use it to
increment all of the elements of an array:
</p>
<pre class="c code c++" style="font-family:monospace;"> template<span class="sy0">&lt;</span>class TYPE<span class="sy0">&gt;</span> <span class="kw4">struct</span> increment <span class="sy0">:</span> public unary_function<span class="sy0">&lt;</span>TYPE<span class="sy0">,</span> void<span class="sy0">&gt;</span> <span class="br0">&#123;</span>
<span class="kw4">void</span> operator<span class="br0">&#40;</span><span class="br0">&#41;</span> <span class="br0">&#40;</span>TYPE<span class="sy0">&amp;</span> x<span class="br0">&#41;</span> <span class="br0">&#123;</span>
x<span class="sy0">++;</span>
<span class="br0">&#125;</span>
<span class="br0">&#125;</span><span class="sy0">;</span>
&nbsp;
...
&nbsp;
<span class="kw4">int</span> nums<span class="br0">&#91;</span><span class="br0">&#93;</span> <span class="sy0">=</span> <span class="br0">&#123;</span>3<span class="sy0">,</span> 4<span class="sy0">,</span> 2<span class="sy0">,</span> 9<span class="sy0">,</span> 15<span class="sy0">,</span> 267<span class="br0">&#125;</span><span class="sy0">;</span>
<span class="kw4">const</span> <span class="kw4">int</span> N <span class="sy0">=</span> <span class="nu0">6</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;Before, nums[] is: &quot;</span><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> N<span class="sy0">;</span> i<span class="sy0">++</span> <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> nums<span class="br0">&#91;</span>i<span class="br0">&#93;</span> <span class="sy0">&lt;&lt;</span> <span class="st0">&quot; &quot;</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> endl<span class="sy0">;</span>
&nbsp;
for_each<span class="br0">&#40;</span> nums<span class="sy0">,</span> nums <span class="sy0">+</span> N<span class="sy0">,</span> increment<span class="sy0">&lt;</span>int<span class="sy0">&gt;</span><span class="br0">&#40;</span><span class="br0">&#41;</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;After, nums[] is: &quot;</span><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> N<span class="sy0">;</span> i<span class="sy0">++</span> <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> nums<span class="br0">&#91;</span>i<span class="br0">&#93;</span> <span class="sy0">&lt;&lt;</span> <span class="st0">&quot; &quot;</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> endl<span class="sy0">;</span></pre>
<p>
The above code displays the following output:
</p>
<pre class="code">
Before, nums[] is: 3 4 2 9 15 267
After, nums[] is: 4 5 3 10 16 268</pre>
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