The SOLID design principles, when combined together, make it easy for a programmer to craft software that is easy to maintain, reuse & extend. Open-Closed Principle(OCP) is the second principle in this series which I will discuss here with minimalistic example in Modern C++ along with its benefits & generic guideline. The code snippets you see throughout this series of articles aresimplified not sophisticated not sophisticated. I also consider myself a pragmatic person who wants to convey an idea in the simplest way possible.