C++ in Quant Jobs

C++ is of course the dominant language in quant finance, utterly outclassing quiche languages like C# or Java.

There is of course an amount of Matlab, R, Mathematica etc, but they are of second order importance.

A large % of C++ in QF is essentially Fortran, and much code in any language is a barbarian horde of fiercely independent functions who only obey a strong leader who has slain his enemies and drunk their blood in a City wine bar.

"Academic" C++ is typically small compared to commercial code, and so you need OO, patterns et al to keep the horde from getting too bolshie. Commercial projects also go on for longer, some C++ code bases in banks is 20 years old, yes really, some of it's mine, so maintenance is a major issue, and re use is of course good.
But you will be asked questions on dangling pointers, stupidly complex type declarations, patterns, and various forms of broken code.
The correlation between real quant coding and what people get asked in interviews is thus not very good.