That's fine provided it really is just a one-to-one copy from index 1 to index 1, index 2 to index 2, etc.

But if getCharacter() does something more useful, like dealing with a circular buffer, there's going to be a lot less in it.

This would be true if you did not validate the transmission.

If you are, indeed, using a circular buffer, then you have two possibilities:

a) read from it to somewhere in the serial module before validating - in that case the transfer from "somewhere" is by my example

b) validate wherever you store that data which would be so much 'non-modular" that the modularity argument would take precedence. In that case you would have to transfer to 'final storage' by either of the examples in my post.

Erik