Question

Does Boost Ranges have a built-in way to cout the elements easily, for example separated by comma or space?

I am of course aware that I could loop over them and print them separately, but it seems to me that this should be built in somehow (like printing a vector in scripting languages).

In an example program I saw, the author copied the range to cout:

boost::copy(range, ostream_iterator(cout, ” “))

Looks ugly to me. Is this idiomatic?

EDIT: A solution for std iterators would also be acceptable.

EDIT2:
What I want to do is this:

cout << range;

But I don’t think that works.
So what I am hoping for is something like this (Python inspired):

cout << range.join(", ");

or perhaps with a range adaptor.

cout << (range | stringify(", "));

Answer 1

I don’t believe it’s ever been really finished/polished, but that’s the intent of Boost.Explore.

Personally, I’ve just gotten used to using std::copy. For this sort of thing, an infix_ostream_iterator can be quite helpful at times. For example, something like this:

#include <vector>
#include <iostream>
#include <algorithm>
#include <iterator>
#include "infix_iterator.h"

template <typename T>
std::ostream& operator<<(std::ostream &o, const std::vector<T>& v) { 
    o << "[";
    std::copy(v.begin(), v.end(), infix_ostream_iterator<T>(o, ", ")); 
    o << "]";
    return o; 
}

int main() { 

    std::vector<int> x;

    for (int i=0; i<20; i+=2)
        x.push_back(i);

    std::cout << x << "\n";
    return 0;
}

As it stands, this has operator<< taking a vector, but it would be relatively trivial to have it take a range instead.