How Can I Implement Python's Zip Function in C Using Boost?

Implementing Sequence-Zipping in C 11 through Boost-Enhanced Range Iteration

One of C 11's key enhancements is the range-based for-loop, simplifying iteration syntax:

for(auto x: Y) {}

This is a significant improvement over previous syntax:

for(std::vector<int>::iterator x=Y.begin(); x!=Y.end(); ++x) {}

The question arises: can this simplified syntax extend to looping over multiple simultaneous sequences, akin to Python's zip function?

Y1 = [1, 2, 3]
Y2 = [4, 5, 6, 7]
for x1,x2 in zip(Y1, Y2):
    print(x1, x2)

This code outputs:

(1,4) (2,5) (3,6)

Solution with Boost's Combine Function

In Boost versions 1.56.0 and later (2014), the boost::combine function can be employed:

#include <boost/range/combine.hpp>

int main() {
    std::vector<int> a {4, 5, 6};
    double b[] = {7, 8, 9};
    std::list<std::string> c {"a", "b", "c"};
    for (auto tup : boost::combine(a, b, c, a)) {    // <---
        int x, w;
        double y;
        std::string z;
        boost::tie(x, y, z, w) = tup;
        printf("%d %g %s %d\n", x, y, z.c_str(), w);
    }
}

This code prints:

4 7 a 4
5 8 b 5
6 9 c 6

Solution with Custom Range Definition (Pre-Boost 1.56.0)

In earlier Boost versions, defining a custom range is necessary:

#include <boost/iterator/zip_iterator.hpp>
#include <boost/range.hpp>

template <typename... T>
auto zip(T&amp;&amp;... containers) -> boost::iterator_range<boost::zip_iterator<decltype(boost::make_tuple(std::begin(containers)...))>>
{
    auto zip_begin = boost::make_zip_iterator(boost::make_tuple(std::begin(containers)...));
    auto zip_end = boost::make_zip_iterator(boost::make_tuple(std::end(containers)...));
    return boost::make_iterator_range(zip_begin, zip_end);
}

The usage remains the same.

Caution for Boost's Zip Iterator

Note that Boost's zip_iterator and boost::combine in Boost versions prior to 1.63.0 (2016) may result in undefined behavior or incorrect iteration if the input container lengths vary.

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