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|
.. Sequences/Intrinsic Metafunctions//back
back
====
Synopsis
--------
.. parsed-literal::
template<
typename Sequence
>
struct back
{
typedef |unspecified| type;
};
Description
-----------
Returns the last element in the sequence.
Header
------
.. parsed-literal::
#include <boost/mpl/back.hpp>
Model of
--------
|Tag Dispatched Metafunction|
Parameters
----------
+---------------+---------------------------+-----------------------------------+
| Parameter | Requirement | Description |
+===============+===========================+===================================+
| ``Sequence`` | |Bidirectional Sequence| | A sequence to be examined. |
+---------------+---------------------------+-----------------------------------+
Expression semantics
--------------------
For any |Bidirectional Sequence| ``s``:
.. parsed-literal::
typedef back<s>::type t;
:Return type:
A type.
:Precondition:
``empty<s>::value == false``.
:Semantics:
Equivalent to
.. parsed-literal::
typedef deref< prior< end<s>::type >::type >::type t;
Complexity
----------
Amortized constant time.
Example
-------
.. parsed-literal::
typedef range_c<int,0,1> range1;
typedef range_c<int,0,10> range2;
typedef range_c<int,-10,0> range3;
BOOST_MPL_ASSERT_RELATION( back<range1>::value, ==, 0 );
BOOST_MPL_ASSERT_RELATION( back<range2>::value, ==, 9 );
BOOST_MPL_ASSERT_RELATION( back<range3>::value, ==, -1 );
See also
--------
|Bidirectional Sequence|, |front|, |push_back|, |end|, |deref|, |at|
.. copyright:: Copyright 2001-2009 Aleksey Gurtovoy and David Abrahams
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
|
