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<title>at</title>
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<a href="../index-2.html">cppreference.com</a> > <a href=
"index.html">C++ Double-ended Queues</a> > <a href=
"at.html">at</a>
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<div class="name-format">
at
</div>
<div class="syntax-name-format">
Syntax:
</div>
<pre class="syntax-box">
#include <deque>
<a href=
"../containers.html">TYPE</a>& at( <strong>size_type</strong> loc );
const <a href=
"../containers.html">TYPE</a>& at( <strong>size_type</strong> loc ) const;
</pre>
<p>The at() function returns a reference to the element in the
dequeue at index <em>loc</em>. The at() function is safer than the []
operator, because it won't let you reference items outside the
bounds of the dequeue.</p>
<p>For example, consider the following code:</p>
<pre class="prettyprint">
vector<int> v( 5, 1 );
for( int i = 0; i < 10; i++ ) {
cout << "Element " << i << " is " << v[i] << endl;
}
</pre>
<p>This code overrunns the end of the vector, producing potentially
dangerous results. The following code would be much safer:</p>
<pre class="prettyprint">
vector<int> v( 5, 1 );
for( int i = 0; i < 10; i++ ) {
cout << "Element " << i << " is " << v.at(i) << endl;
}
</pre>
<p>Instead of attempting to read garbage values from memory, the at()
function will realize that it is about to overrun the vector and will
throw an exception.</p>
<div class="related-name-format">
Related topics:
</div>
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(C++ Multimaps) <a href=
"../cppmultimap/multimap_operators.html">Multimap
operators</a><br>
<a href="container_operators.html">Deque operators</a>
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