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c++algorithmc++11iteratorstdset

How to iterate std::set based on offset from set.begin()?

I need to get an iterator based on offset.

i.e. having the iterator for begin :

auto it = set.begin()

I need to get to the iterator having offset ofst:

it + ofst

Is there a way to do that? of I need incremental increase it++ the iterator ofst times.

Solution

  • I need to get to the iterator having offset ofst: it + ofst: is there a way to do that?

    No, there is no operator+ overload defined for this for std::set::iterator (aka bidirectional iterators). However, you can use std::next, from <iterator> header as follows to achive the same.

    #include <iterator>  // std::next

auto nthIter = std::next(it, ofst);

    This basically behind the scene increments ofst times too.

    The std::set has bidirectional iterators, which has no luxuries like random access iterators, and hence need to increment like this.

    That being said, you could overload the operator+(and maybe operator-) for the bidirectional iterators, which will not be recommended though.