Re: [Boost-users] Searching through a vector of tuples...

From: Richard Dingwall (rdingwall_at_[hidden])
Date: 2007-08-13 19:54:44

The following appears to work (it compiles :)):

#include <boost/tuple/tuple.hpp>
#include <boost/bind.hpp>
#include <vector>
#include <algorithm>
#include <cassert>

template<int N, class tuple_type> inline
typename boost::tuples::element<N, tuple_type>::type & get(tuple_type & t)
{
    return boost::tuples::get<N>(t);
}

int main(const int argc, const char ** argv)
{

    typedef boost::tuples::tuple<int, double> some_tuple;

    std::vector<some_tuple> vec_of_some_tuples;

    std::vector<some_tuple>::iterator
result(std::find_if(vec_of_some_tuples.begin(), vec_of_some_tuples.end(),
boost::bind(get<0, some_tuple>, ::_1) == 42));

    assert(result != vec_of_some_tuples.end());

    return 0;
}

Where 42 is the item you're looking for. See this post for original get():
http://lists.boost.org/boost-users/2007/01/24529.php

Otherwise, use a map?

Richard

On 8/14/07, David Abrahams <dave_at_[hidden]> wrote:
>
>
> on Mon Aug 13 2007, "Graham Reitz" <graham.cpp-AT-gmail.com> wrote:
>
> > typedef boost::tuples::tuple<int,double> some_tuple;
> >
> > std::vector<some_tuple> vec_of_some_tuples;
> >
> > // ... stuff some data into the vector
> >
> > // ... search for a specific int in the vector of some_tuple
> >
> > What would be a good method, using an stl algorithm, to search through
> > the vector above to match only the int portion of the tuple (ignoring
> > the double)?
>
> Use std::find with a boost::transform_iterator over a function
> returning the first member of the tuple, then extract the resulting
> iterator's base() iterator.
>
> HTH,
>
> --
> Dave Abrahams
> Boost Consulting
> http://www.boost-consulting.com
>
> The Astoria Seminar ==> http://www.astoriaseminar.com
>
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