But there is an error in file b.rs when I am tring to write "mod b.rs;" to file a.rs.
Why is this happening? What is the reason of this problem? And how can I fix this?
I'm not sure exactly what your issue is, but here's a tip: before you start to break things up into files, first figure out how you want to define modules. Maybe you want something like this?
// main.rs or lib.rs
mod a {
/* ??? */
}
mod b {
mod c {
pub struct Number {}
}
}
Start with all code in the same file and modules defined in-line. Get it working that way first, and only then start breaking out modules into their own files.