[defrost]

Expanding on neuroguy's comment, there's many different people working on making models and pretty much (<simplification>) the only things that matter here are the collections of transfer functions; given inputs, how do outputs propagate. You can see that in the C++ (well, C from the looks of it) example you gave, there's a time value, a timestep, a bunch of physical attributes, and a series of functions - no matter what the language or system used all the other models there have similar features.

When people look at the work of others they are less interested in the modelling system used and more interested in the model, which most are happy to translate to whatever system they are using as the very act of crawling through and translating from one form to another forces a certain kind of deeper look at the details.

It's on par with Watson & Crick using plasticine and paddlepop sticks for their model while others use ping pong balls and wire coat hangers ... further down the track everything gets unified but at the early stages one form of modelling is more or less as good as another.