Defining modules in Rust - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a module in Rust?

A module in Rust is a way to organize code into separate namespaces. It helps group related functions, structs, and other items together, making code easier to manage and understand.

beginner

How do you define a module inside a Rust file?

You define a module using the mod keyword followed by the module name and curly braces containing the module's code. For example:

mod greetings { fn hello() { println!("Hi!"); } }

intermediate

What is the difference between mod and use in Rust modules?

mod defines a new module or declares it exists, while use brings items from a module into scope so you can use them without full paths.

beginner

How do you make a function inside a module accessible from outside the module?

You add the pub keyword before the function to make it public. For example:

pub fn greet() { println!("Hello!"); }

Without pub, the function is private to the module.

intermediate

How can you split a module into multiple files in Rust?

You create a folder with the module name and add a mod.rs file inside it, or in newer Rust versions, create a file named after the module. Then, submodules are files inside that folder. This helps organize large modules.

Which keyword is used to define a module in Rust?

A fn

B use

C mod

D pub

The mod keyword defines a module in Rust.

How do you make a function inside a module accessible from other modules?

A Use <code>use</code> before the function

B Use <code>mod</code> before the function

C Functions are always accessible

D Add <code>pub</code> before the function

Functions are private by default. Adding pub makes them accessible outside the module.

What does the use keyword do in Rust modules?

A Defines a new module

B Imports items from a module into scope

C Makes a function public

D Deletes a module

use brings items from a module into the current scope for easier access.

If you define mod greetings {} inside main.rs, where can you use the items inside greetings?

A Anywhere in the crate if items are public

B Only inside <code>greetings</code>

C Only outside <code>greetings</code>

D Nowhere

Public items inside a module can be used anywhere in the crate.

How can you organize a large module into multiple files?

A By creating submodules in separate files

B By putting all code in one file

C By using <code>use</code> to import files

D Rust does not support multiple files for modules

Large modules can be split into submodules placed in separate files or folders.

Explain how to define a module in Rust and make a function inside it accessible from outside.

Think about keywords to create modules and control access.

Describe how Rust modules help organize code and how you can split modules into multiple files.

Consider how big projects keep code tidy.