mirror of
https://github.com/boostorg/mpl.git
synced 2026-01-26 08:52:21 +01:00
61 lines
2.8 KiB
HTML
61 lines
2.8 KiB
HTML
<!doctype html public "-//ietf//dtd html//en">
|
|
<html><head><title>boost::mpl::equal_to</title>
|
|
<link rel="stylesheet" href="../mpl_wiki.css">
|
|
</head><body bgcolor="white">
|
|
<h1><a href="../Table_of_Contents.html"><img src="../mpl_logo.jpg" alt="[Home]" border=0 align="right"></a>equal_to</h1><h3>Synopsis</h3>
|
|
<p>
|
|
<pre>
|
|
template<
|
|
typename T1
|
|
, typename T2
|
|
>
|
|
struct equal_to
|
|
{
|
|
typedef <em>unspecified</em> type;
|
|
};
|
|
</pre>
|
|
<p>
|
|
<h3>Description</h3>
|
|
<p>
|
|
Returns <code>true_</code> if <code>T1::value == T2::value</code> and <code>false_</code> otherwise [<a href="#1">1</a>].
|
|
<p>
|
|
<h3>Definition</h3>
|
|
<p>
|
|
<pre>
|
|
#include "<a href="../../../../../boost/mpl/equal_to.hpp">boost/mpl/equal_to.hpp</a>"
|
|
</pre>
|
|
<p>
|
|
<h3>Parameters</h3>
|
|
<table border="1">
|
|
<tr><th> Parameter </th><th> Requirement </th><th> Description </th></tr>
|
|
<tr><td><code>T1, T2</code></td><td>A model of <a href="../Integral_Constant.html">Integral Constant</a></td><td></td></tr>
|
|
</table>
|
|
<p>
|
|
<h3>Expression semantics</h3>
|
|
<p>
|
|
<table border="1">
|
|
<tr><th> Expression </th><th> Expression type </th><th> Precondition </th><th> Semantics </th><th> Postcondition </th></tr>
|
|
<tr><td><code>typedef equal_to<t1,t2>::type c;</code></td><td>A model of <code>bool</code> <a href="../Integral_Constant.html">Integral Constant</a></td><td></td><td>Equivalent to <code>typedef bool_<(t1::value == t2::value)> c;</code></td><td></td></tr>
|
|
</table>
|
|
<p>
|
|
<h3>Complexity</h3>
|
|
<p>
|
|
Amortized constant time.
|
|
<p>
|
|
<h3>Example</h3>
|
|
<p>
|
|
<pre>
|
|
typedef <a href="../Reference/list_c.html">list_c</a><int,1,2,3,5,7,12,19,31> fibonacci;
|
|
typedef <a href="../Reference/find_if.html">find_if</a>< fibonacci, equal_to<_1,int_<12> > >::type iter;
|
|
BOOST_STATIC_ASSERT(equal_to< <a href="../Reference/distance.html">distance</a>< <a href="../Reference/begin.html">begin</a><fibonacci>::type, iter >::type, int_<5> >::type::value));
|
|
</pre>
|
|
<p>
|
|
<h3>Notes</h3>
|
|
<p>
|
|
[<a name="1">1</a>] The <code>equal_to</code> metafunction can be (and is expected to be) specialized by user to work on user-defined types that do not satisfy the <a href="../Integral_Constant.html">Integral Constant</a> requirements. The requirements listed here are the ones imposed by the default implementation.<br>
|
|
<p>
|
|
<h3>See also</h3>
|
|
<p>
|
|
<a href="../Metafunctions.html">Metafunctions</a>, <code><a href="../Reference/not_equal_to.html">not_equal_to</a></code>, <code><a href="../Reference/less.html">less</a></code>, <code><a href="../Reference/less_equal.html">less_equal</a></code>, <code><a href="../Reference/greater.html">greater</a></code>, <code><a href="../Reference/greater_equal.html">greater_equal</a></code>
|
|
<p><hr>
|
|
<a href="../Table_of_Contents.html">Table of Contents</a><br>Last edited March 10, 2003 6:26 am</body></html> |