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<div class="titlepage"><div><div><h3 class="title">
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<a name="fusion.tuple.pairs"></a><a href="pairs.html" title="Pairs">Pairs</a></h3></div></div></div>
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<a name="fusion.tuple.pairs.description"></a><h4>
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<a href="pairs.html#fusion.tuple.pairs.description">Description</a>
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<p>
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The <a href="http://std.dkuug.dk/jtc1/sc22/wg21/docs/papers/2002/n1403.pdf" target="_top">TR1
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Tuple</a> interface is specified to provide uniform access to <tt class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></tt>
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as if it were a 2 element tuple.
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</p>
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<a name="fusion.tuple.pairs.specification"></a><h4>
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<a name="id642964"></a>
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<a href="pairs.html#fusion.tuple.pairs.specification">Specification</a>
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</h4>
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<pre class="programlisting">
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<span class="identifier">tuple_size</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">></span> <span class="special">>::</span><span class="identifier">value</span>
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</pre>
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<p>
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<span class="bold"><b>Type</b></span>: An <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL
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Integral Constant</a>
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</p>
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<p>
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<span class="bold"><b>Value</b></span>: Returns 2, the number of elements
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in a pair.
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</p>
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<pre class="programlisting">
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<span class="identifier">tuple_element</span><span class="special"><</span><span class="number">0</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">></span> <span class="special">>::</span><span class="identifier">type</span>
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</pre>
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<p>
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<span class="bold"><b>Type</b></span>: <tt class="computeroutput"><span class="identifier">T1</span></tt>
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</p>
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<p>
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<span class="bold"><b>Value</b></span>: Returns the type of the first element
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of the pair
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</p>
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<pre class="programlisting">
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<span class="identifier">tuple_element</span><span class="special"><</span><span class="number">1</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">></span> <span class="special">>::</span><span class="identifier">type</span>
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</pre>
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<p>
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<span class="bold"><b>Type</b></span>: <tt class="computeroutput"><span class="identifier">T2</span></tt>
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</p>
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<p>
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<span class="bold"><b>Value</b></span>: Returns thetype of the second element
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of the pair
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</p>
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<pre class="programlisting">
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">int</span> <span class="identifier">I</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T2</span><span class="special">></span>
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<span class="identifier">P</span><span class="special">&</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">>&</span> <span class="identifier">pr</span><span class="special">);</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">int</span> <span class="identifier">I</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T2</span><span class="special">></span>
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<span class="keyword">const</span> <span class="identifier">P</span><span class="special">&</span> <span class="identifier">get</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">>&</span> <span class="identifier">pr</span><span class="special">);</span>
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</pre>
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<p>
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<span class="bold"><b>Type</b></span>: If <tt class="computeroutput"><span class="identifier">I</span>
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<span class="special">==</span> <span class="number">0</span></tt>
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<tt class="computeroutput"><span class="identifier">P</span></tt> is <tt class="computeroutput"><span class="identifier">T1</span></tt>,
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else if <tt class="computeroutput"><span class="identifier">I</span> <span class="special">==</span>
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<span class="number">1</span></tt> <tt class="computeroutput"><span class="identifier">P</span></tt>
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is <tt class="computeroutput"><span class="identifier">T2</span></tt> else the program is
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ill-formed.
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</p>
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<p>
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<span class="bold"><b>Returns: <tt class="computeroutput"><span class="identifier">pr</span><span class="special">.</span><span class="identifier">first</span></tt>
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if <tt class="computeroutput"><span class="identifier">I</span> <span class="special">==</span>
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<span class="number">0</span></tt> else <tt class="computeroutput"><span class="identifier">pr</span><span class="special">.</span><span class="identifier">second</span></tt>.</b></span>[*Returns:
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<tt class="computeroutput"><span class="identifier">pr</span><span class="special">.</span><span class="identifier">first</span></tt> if <tt class="computeroutput"><span class="identifier">I</span>
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<span class="special">==</span> <span class="number">0</span></tt>
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else <tt class="computeroutput"><span class="identifier">pr</span><span class="special">.</span><span class="identifier">second</span></tt>.
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</p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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