[Kristine1975]

Xcode checks your code as you type (90% of the time, sometimes early errors, e.g. in a header, make it give up completely on a file). Compiling still is a separate step. Current versions of VS do the same, though, even for C++.

[roel_v]

Visual studio compiles as you type. It has to, to work with e.g. 'auto'. Vs has two compilers actually, one that compiles as you type (and tries to guess what you mean more), and one for the real compile cycle.