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?

No, it is not "equivalent to #define". This is correct C++ syntax, so, in that sense, it is "correct" to use it. — Sam Varshavchik, Dec 18 '16 at 17:09
It's actually an alternative to `typedef`, but more flexible. Consider this more complex version: `template using v = vector;` — Justin Time - Reinstate Monica, Dec 18 '16 at 17:17

score 2 · Answer 1 · edited May 23 '17 at 12:24

2

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.

edited May 23 '17 at 12:24

Community

answered Dec 18 '16 at 17:13

Anton

1 Answers1