cpp/experimental/ranges/iterator/distance

Returns the distance between and, or between the beginning and the end of the range.

@1@ If is satisfied, equivalent to. Otherwise, returns the number of increments needed to get from to. If does not denote a range, then  and  must be the same type and must model, and  must denote a range. Otherwise, the behavior is undefined. @2@ Equivalent to @3@ Equivalent to

Instantiating overloads may be ill-formed if the header  is not included before the point of instantiation.

Return value
The distance between and, or between the beginning and the end of the range.