Please guide me, how do you enable autocomplete functionality in VS C++? By auto-complete, I mean, when I put a dot after control name, the editor should display a dropdown menu
It's enabled by default. Probably you just tried on an expression that failed to autocomplete.
In case you deactivated it somehow... you can enable it in the Visual Studio settings. Just browse to the Editor settings, then to the subgroup C/C++ and activate it again... should read something like "List members automatically" or "Auto list members" (sorry, I have the german Visual Studio).
Upon typing something like std::cout. a dropwdownlist with possible completitions should pop up.