In C++ you could even consider using the STL library, but these will often use memory allocation. Memory allocation is often undesirable, so there are
static STL libraries (3rd party) that are more tailored towards embedded.
Then again you may still want to consider not using C++ at all.
In C, you can use printf() to print serial data. But where will it appear? Some manufacturers will include, often part of the boilerplate code for a chip or compiler, a char redirection function that for example always spits out the data on the first UART of the chip. You could redirect this to another peripheral.. doesn't even have to be UART.
But does it make sense to use getch or sscanf? They are polling functions. Have never tried actually, but conceptually it doesn't make much sense to program that way on embedded.
In particular, I think many embedded compilers won't support the stdin/stdout/stderr file streams.