The number of river reaches can be passed to the argument lngNum_RS. But in other languages (for example, python), this "passing by reference" mechanism might not work and with python, I can't get the number of river reaches in the same way.
I think my question is, what is the general rule to use this type of "passing by reference" functions in HECRAS Controller with python? Do we have a document for the HECRASController COM in python?
I am starting on C++ project to interact with HEC-RAS and so am interested in this forum and will probably purchase the "Breaking the HEC-RAS Code" book.
However, I have found that you can look inside the ras.exe from within VisualStudio (menu view->object browser, then select Custom Component Set, click on the "..." button and find the HEC River Analysis System under the COM tab). From there you can see at least the functions and their parameters.