| Home | Libraries | People | FAQ | More

##### front

###### Description

Returns the first element in the sequence.

###### Synopsis

    template <typename Sequence>
    typename result_of::front<Sequence>::type
    front(Sequence& seq);

    template <typename Sequence>
    typename result_of::front<Sequence const>::type
    front(Sequence const& seq);

###### Parameters

Parameter | Requirement | Description
--- | --- | ---
`seq` | Model of Forward Sequence | The sequence we wish to investigate.

###### Expression Semantics

    front(seq);

Return type: Returns a reference to the first element in the sequence `seq` if `seq` is mutable and `e = o`, where `e` is the first element in the sequence, is a valid expression. Else, returns a type convertible to the first element in the sequence.

Precondition: ``empty`(seq) == false`

Semantics: Returns the first element in the sequence.

###### Header

    #include <boost/fusion/sequence/intrinsic/front.hpp>
    #include <boost/fusion/include/front.hpp>

###### Example

    vector<int, int, int> v(1, 2, 3);
    assert(front(v) == 1);