Python-like loop enumeration in C++ [duplicate]

Answer 1

As @Kos says, this is such a simple thing that I don't really see the need to simplify it further and would personally just stick to the traditional for loop with indices, except that I'd ditch std::vector::size_type and simply use std::size_t:

for(std::size_t i = 0; i < v.size(); ++i)
    foo(v[i], i);

I'm not too keen on solution 2. It requires (kinda hidden) random access iterators which wouldn't allow you to easily swap the container, which is one of the strong points of iterators. If you want to use iterators and make it generic (and possibly incur a performance hit when the iterators are not random access), I'd recommend using std::distance:

for(auto it(v.begin()); it != v.end(); ++it)
    foo(*it, std::distance(it, v.begin());