Question

I’m using the boost::iostream lib to wrap a posix pipe to gnuplot. To send binary inline data to gnuplot, I’m currently doing something like this

std::vector<double> d = test_data();
Gnuplot plt; //custom gnuplot class derived from boost::iostream::stream

plt << "plot '-' binary format='%double' notitle\n"
plt.write( (char*)( &c.front() ), sizeof(double)*c.size() ); // send binary data

It works, but I’d like to get rid of .write and use an iterator interface to allow e.g. a std::list as source. I know std::ostreambuf_iterator allows unformatted input but simply using std::copy obviously doesn’t work.

Answer 1

Here’s a naive wrapper template to write out ranges:

#include <memory>
#include <iterator>

template <typename FwdIter>
write_range(Gnuplot & gp, FwdIter it, FwdIter end)
{
    typedef typename std::iterator_traits<FwdIter>::value_type type;
    for ( ; it != end; ++it)
    {
        gp.write(reinterpret_cast<char const *>(std::addressof(*it)), sizeof(type));
    }
}

Usage: write_range(gp, mylist.begin(), mylist.end());