Wrote C++, C# and Java, since I'm currently employed for a position in Java with bits and pieces of other things, including SQL, Apache, and perhaps Javascript (something that we may add eventually)
C# I've had classes of it in University and I've made some projects in Unity with it.
C++ was the first language I ever started learning and I've done multiple little programs and I'm starting to dwell into UE4, which implements C++ as well.
Eventually, I'd like to gain more experience with OpenGL or even DirectX as well, since I'd like to be an Engine/Networking/Graphics Engineering. For most big companies/software, C++ is the go-to requirement.
OpenGL and DirectX experience is valued as well a lot, and I am really interested in getting into that later on since I'd like to make things from "scratch" (you never really do anything from 100% scratch, hence the quotation marks), but I'm still going with Unity and UE4 because the "reward" or "interest" response I get from them are obviously more frequent than by learning more of C++ and/or OpenGL.
You've seen my GUI Poker, which I will add a betting system later. Will also probably rewrite pieces of the code to essentially have "Player" classes to use as objects, allowing further on to have multiple "human" players, instead of human vs computer.
Also, as far as C# is concerned, some GTA5 hobby/interest may come soon
Edit: also, I'd pick a different title since most of us will misunderstand the fact that one can get to "know" a language. Something so vast and with such continuous growth will never be "known" to a single person,
hence the importance of a team and individuals who are very strong in one area, without being oblivious to others.