Project with Cargo

Learn to set up a project with cargo new, Cargo.toml and the target folder.

Projects with Cargo

Cargo is Rust's build tool and package manager. It creates new projects, downloads dependencies, builds, runs and tests:

cargo new merhaba     # new project
cd merhaba
cargo run             # build and run
cargo build --release # optimized build
cargo test            # run tests

cargo new creates a Cargo.toml file and src/main.rs.

Cargo.toml

Cargo.toml holds the project's identity and dependencies:

[package]
name = "merhaba"
version = "0.1.0"
edition = "2021"

[dependencies]
rand = "0.8"

The exact versions of dependencies are written to Cargo.lock, so the same versions are used on every machine. Packages are downloaded from crates.io.

Exercise Package info

Cargo provides the package name and version as environment variables during the build. Try it with fixed values instead of env!("CARGO_PKG_NAME"): declare let ad = "merhaba"; let surum = "0.1.0"; and print println!("{} v{}", ad, surum);.

Show example solution

fn main() {
    let ad = "merhaba";
    let surum = "0.1.0";
    println!("{} v{}", ad, surum);
}

Test yourself

What is the difference between <code>cargo build --release</code> and <code>cargo build</code>?
- --release optimizes; output goes under target/release
- --release runs the tests
- There is no difference
- --release publishes the code
Show answer

--release optimizes; output goes under target/release — The default build compiles fast but runs slowly (target/debug); --release compiles slowly but runs much faster.

Run

cargo ____   # builds and runs

Show answer

cargo run   # builds and runs

Command and role

cargo new

Creates a project
cargo run

Builds and runs
cargo test

Runs the tests
Cargo.lock

Exact versions

Next lesson: Your first program

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