String concatenation

[Kyon]

Hey forum,
I've yet another question, this time, regarding string (literals). The question I have is, when I use tri- or digraphs, I may not be able to put ?? in a string literal without strange behavior. I have two options to avoid this strange behavior. One is using an escape sequence \? (or the trigraph brother of that). The other is using string concatenation. Is string concatenation pre-processed by the compiler or the string literals being added together on runtime (and does this come with "drastic" changes to performance, whatsoever).

Thanks in advance.

[Skillless]

By the compiler,

for example \n , newline, is a single char, though in your code, its 2 characters long

[Kyon]

I'm talking about string (literal) concatenation. Not escape sequences. When I type "bla" "blabla" I wonder if they are added to each other during compile time (since they really are constant literals), or if they are added together during runtime, which would mean that they take unnecessary processor work. I have this question because there's two ways of avoiding the tri- or digraphs, one which is this one, and another is escape sequences (which I really dislike myself).