How to split modules across files

Split modules across files by creating a new file for the module and declaring it with mod in the parent file.

1. Create a new file named my_module.rs in the same directory as your main.rs.
2. Add mod my_module; to your main.rs to declare the module.
3. Define your items inside my_module.rs and access them using my_module::item_name in main.rs.

// main.rs
mod my_module;

fn main() {
    my_module::greet();
}

// my_module.rs
pub fn greet() {
    println!("Hello from a separate file!");
}

Splitting modules across files keeps your code organized by grouping related logic into separate documents. Think of it like moving chapters of a book into their own files so the main story remains easy to read. You tell Rust where these files are using the mod keyword, allowing you to use their functions without cluttering your main program.