Grant Erickson wrote:
For a recent project, I needed to inquire about a sequence of objects and make a determination as to whether the sequences were:
* Increasing * Strictly Increasing * Decreasing * Strictly Decreasing
Looking through STL, Boost documentation, Boost sources and headers and the Boost mailing lists I was able to find neither an existing algorithm or stateful unary predicate functor for accomplishing this for a pair of input iterators. However, I was a bit surprised considering that this seems like a sequence property query that would tend to come up fairly often and serve a general utility. Did I just fail to form the proper search/query or am I overestimating the general utility?
Regardless, I forged ahead with the rather naïve implementation (see below), which can be used as a predicate with for_each as shown: <snip> Regards,
Grant
Perhaps std::adjacent_find and std::less is all you need, e.g., to determine if a sequence is decreasing? I.e., a sequence is decreasing iff all adjacent pairs of elements xi, x[i+1] satisfies xi >= x[i+1] iff no adjacent pair of elements xi, x[i+1] satisfies xi < x[i+1] (assuming that (!>=) == (<)). - Jeff