New to Rust? We recommend checking out Rust by Example to get up to speed.

Local development

To run the code for your challenge locally, you’ll need cargo installed. Our test runners use version 1.76 (as of April 2024).

The script for your challenge (like ./ will automatically compile and run your code using cargo run. It’ll look something like this:


exec cargo run \
    --quiet \
    --release \
    --target-dir=/tmp/codecrafters-bittorrent-target \
    --manifest-path $(dirname "$0")/Cargo.toml -- "$@"

File structure

  • The files for your solution are placed in the src directory.
  • src/ contains the main function, which is what the test runner executes.

Adding more files

You can add more files and directories to the src directory. The test runner will include them when compiling your code.

For example, if you added a file at src/, you could use it like so:

pub fn foo() {
    println!("Hello World!");

Remember to make foo() accessible to by adding the pub identifier

Adding dependencies

You can add dependencies to your program using cargo add.

For example, to add the rand crate, run the following command:

cargo add rand

This command will automatically find the latest version of the rand crate and add it to your Cargo.toml file:

rand = "0.8.5"

It’ll also make changes to your Cargo.lock file.