nrr_enumerate

Python-like 'enumerate' for C++

Python and some other languages have a handy built-in function called enumerate(), which lets you iterate over an object (e.g. a list) and have access to both the index and the item in each iteration. This header gives a C++17/20 implementation of the same idea. Use it like:

std::vector<Thing> things;
...
for (auto [i, thing] : enumerate(things))
{
    // i gets the index and thing gets the Thing in each iteration
}

Iterating over things itself would give you thing, but not i, and there are plenty of situations where you want both. See the accompanying blog post for more info.

There's also a const version, cenumerate(), which iterates the given object as const. (Sadly, using const auto [i, thing] doesn't actually do the job, because of reasons.)