Boost C++ Libraries

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at_c
Description

Returns the result type of at_c[8].

Synopsis
template<
    typename Seq,
    int N>
struct at_c
{
    typedef unspecified type;
};

Table 1.29. Parameters

Parameter

Requirement

Description

Seq

A model of Random Access Sequence

Argument sequence

N

Positive integer index

Index of element


Expression Semantics
result_of::at_c<Seq, N>::type

Return type: Any type

Precondition: 0 <= N < result_of::size<Seq>::value (where Seq is not Unbounded Sequence)

Semantics: Returns the result type of using at_c to access the Nth element of Seq.

Header
#include <boost/fusion/sequence/intrinsic/at.hpp>
#include <boost/fusion/include/at.hpp>
Example
typedef vector<int,float,char> vec;
BOOST_MPL_ASSERT((boost::is_same<result_of::at_c<vec, 1>::type, float&>));


[8] result_of::at_c reflects the actual return type of the function at_c. Sequence(s) typically return references to its elements via the at_c function. If you want to get the actual element type, use result_of::value_at_c


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