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43 lines
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43 lines
3.0 KiB
HTML
<!doctype html public "-//ietf//dtd html//en">
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<html><head><title>boost::mpl::Integral Constant</title>
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<link rel="stylesheet" href="./mpl_wiki.css">
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<h1><a href="./Table_of_Content.html"><img src="./mpl_logo.jpg" alt="[Home]" border=0 align="right"></a>Integral Constant</h1><h3>Description</h3>
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<p>
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An Integral Constant is a class (or a template class) that represents a value of a built-in integral type (<code>bool</code>, <code>int</code>, <code>long</code>, etc.) in compile-time programs. An integral constant directly supports the increment/decrement operations within the range of the built-in integral type it wraps. Other arithmetic operations are supported through the external metafunctions.
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<p>
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<h3>Valid expressions</h3>
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<p>
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<table border="1">
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<tr><th> Expression </th><th> Return type </th></tr>
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<tr><td><code>typename n::value_type</code></td><td>An <em>integral type</em> </td></tr>
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<tr><td><code>typename n::type</code></td><td>A model of <a href="./Integral_Constant.html">Integral Constant</a> </td></tr>
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<tr><td><code>n::value</code></td><td>A compile-time integral constant of <code>n::value_type</code> </td></tr>
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<tr><td><code>typename n::next</code></td><td>A model of <a href="./Integral_Constant.html">Integral Constant</a> </td></tr>
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<tr><td><code>typename n::prior</code></td><td>A model of <a href="./Integral_Constant.html">Integral Constant</a> </td></tr>
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</table>
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<p>
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<h3>Expression semantics</h3>
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<p>
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<table border="1">
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<tr><th> Expression </th><th> Complexity </th><th> Precondition </th><th> Semantics </th><th> Postcondition </th></tr>
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<tr><td><code>typename n::value_type</code></td><td>Amortized constant time</td><td></td><td><code>n::value_type</code> is identical to <code>typeof(n::value)</code></td><td></td></tr>
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<tr><td><code>typename n::type</code></td><td>Amortized constant time</td><td></td><td>Self-reference.</td><td><code>is_same<n::type,n>::value == true</code> </td></tr>
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<tr><td><code>n::value</code></td><td>Amortized constant time</td><td></td><td>Value of <code>n</code>.</td><td></td></tr>
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<tr><td><code>typename n::next</code></td><td>Amortized constant time</td><td><code>n::value_type</code> supports an increment operation; <code>n::value</code> is incrementable</td><td>Increment operation</td><td><code>n::next::value == n::value + 1</code> </td></tr>
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<tr><td><code>typename n::prior</code></td><td>Amortized constant time</td><td><code>n::value_type</code> supports an decrement operation; <code>n::value</code> is decrementable</td><td>Decrement operation</td><td><code>n::next::value == n::value - 1</code> </td></tr>
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</table>
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<p>
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<h3>Models</h3>
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<p>
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<ul>
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<li><code>integral_c</code>
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<li><code>int_c</code>
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<li><code>bool_c</code>
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</ul>
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<p>
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<h3>See also</h3>
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<p>
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<code><a href="./Reference/next.html">next</a></code>, <code><a href="./Reference/prior.html">prior</a></code>
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<p><hr>
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<a href="./Table_of_Content.html">Table of Content</a><br>Last edited July 17, 2002 7:05 am</body></html> |