A simple standard C++ hello world introduces: functions, ctors, dtors, headers, header guards (you are including headers right away), namespaces (std, anonymous

A simple standard C++ hello world introduces: functions, ctors, dtors, headers, header guards (you are including headers right away), namespaces (std, anonymous), operator overloading (<<), function overloading, pointer to function (endl), templates, traits, locales, streams (basic_ostream), lifetimes (cout), move operations, inheritance, static initialization (in locales) and a bunch of other things I surely missed.