Boost C++ Libraries

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at

Description

Returns the result type of at ^[6] .

Synopsis

template<
    typename Seq,
    typename N>
struct at
{
    typedef unspecified type;
};

Table 1.25. Parameters

Parameter	Requirement	Description
`Seq`	A model of Forward Sequence	Argument sequence
`N`	An MPL Integral Constant	Index of element

Expression Semantics

result_of::at<Seq, N>::type

Return type: Any type.

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

/sequence/intrinsic/at.hpp>

Example

typedef vector<int,float,char> vec;
BOOST_MPL_ASSERT((boost::is_same<result_of::at<vec, boost::mpl::int_<1> >::type, float&>));

^[6] result_of::at reflects the actual return type of the function at. Sequence(s) typically return references to its elements via the at function. If you want to get the actual element type, use result_of::value_at