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The MPL Reference Manual: back
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back

Synopsis

template<
      typename Sequence
    >
struct back
{
    typedef unspecified type;
};

Description

Returns the last element in the sequence.

Parameters

Parameter Requirement Description
Sequence Bidirectional Sequence A sequence to be examined.

Expression semantics

For any Bidirectional Sequence s:

typedef back::type t;
Return type:

A type.
Precondition:

empty::value == false.
Semantics:

Equivalent to

typedef deref< prior< end::type >::type >::type t;

Complexity

Amortized constant time.

Example

typedef range_c range1;
typedef range_c range2;
typedef range_c range3;

BOOST_MPL_ASSERT_RELATION( back::value, ==, 0 );
BOOST_MPL_ASSERT_RELATION( back::value, ==, 9 );
BOOST_MPL_ASSERT_RELATION( back::value, ==, -1 );
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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)