I am an embedded programmer and I was wondering is it possible to program embedded microcontrollers using C or C++.
STM32 works on C language but other boards like Arduino or Raspberry Pi, can we program them in C?
With an Arduino, at least, you can use both (among others) with the appropriate Arduino-based libraries.
No...wait you didn't miss it 'cos you asked about it...I misread what you posted...need coffee.
I am not sure that a lot of embedded things support C++ fully. C is commonly used on many things. If it supports C++ at all, you may find some of the more exotic things to be missing on some systems.