26 Ranges library [ranges]

26.7 Range adaptors [range.adaptors]

26.7.13 Join with view [range.join.with]

26.7.13.1 Overview [range.join.with.overview]

join_­with_­view takes a view and a delimiter, and flattens the view, inserting every element of the delimiter in between elements of the view.
The delimiter can be a single element or a view of elements.
The name views​::​join_­with denotes a range adaptor object ([range.adaptor.object]).
Given subexpressions E and F, the expression views​::​join_­with(E, F) is expression-equivalent to join_­with_­view(E, F).
[Example 1: vector<string> vs = {"the", "quick", "brown", "fox"}; for (char c : vs | views::join_with('-')) { cout << c; } // The above prints the-quick-brown-fox — end example]