[Help]Concatenate byte arrays

I'm stumped on how to do this (efficiently). /:

I'm not sure if there is any way to do that at compile time without using #defines. I'm talking about something like this:
I'm sure there is a less hacky way to do it though.

I want to do this at run time O:

I know I can just iterate through each byte and assign it, but is there a function that does it for me? (a C++ function that may be more efficient or faster or something_

//b-bump? S:

1. Don't double post.
2. The fastest you could get this at run-time would probably using memcpy to copy the bytes.

malloc & memcpy