Use of "using" keyword as pseudo-preprocessor

Question

I've recently come across:

using vi = vector<int>;
using mvi = map<vi, int>;

Is it equivalent to #define? Is it correct to use this?

Answer 1

This particular form has the same functionality as typedef. See this post for a good explanation of the using keyword: What is the logic behind the "using" keyword in C++?

Also, it is not the same as #define. That is a pre-processor macro.