What is an indicator? It is a set of calculated values that we want to be displayed on the screen in a convenient way. Sets of values are represented in programs as arrays. Thus, creation of an indicator means writing an algorithm that handles some arrays (price arrays) and records results of handling to other arrays (indicator values). By describing creation of True Strength Index, the author shows how to write indicators in MQL5.
This is just a brief review of MetaTrader 5. I can't describe all the system's new features for such a short time period - the testing started on 2009.09.09. This is a symbolical date, and I am sure it will be a lucky number. A few days have passed since I got the beta version of the MetaTrader 5 terminal and MQL5. I haven't managed to try all its features, but I am already impressed.