std::for_each index

[hallow iris]

Is there an easy, standard method of acquiring the index of the current element from within the function/lambda? Something like:

std::for_each(std::par_unseq, vec.begin(), vec.end(), [](int element, size_t index)
{});

Additionally, are there any similar functions which allow doing a similar thing? I need the par_unseq. Something where the function parameter accepts an index rather than an element would be ideal.

[pure pelican]

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[frank yew]

no, but you can just use a regular for-loop

std::for_ech is mostly a legacy construct from before range-based for loops were a thing

[hallow iris]

range based for loops don't have the execution policy though, right? so it would require manual parallelization

[frank yew]

yeah

[hallow iris]

hmm, so i basically have to do this as there's nothing in the stl

[frank yew]

you could probably make an iterator that returns itself when dereferenced, so you get the original iterator in the call that for_each makes

and then you can use the iterator difference to get the index

or if it's for a contiguous range like a std::vector, you can get the index by getting the pointer difference from the first element

[hallow iris]

hmm ok thanks

!solved