Rusty Projects — Chapter 01

Practice Rust with several projects | Creative Projects for Rust Programmers
By Carlo Milanesi.

This is the note of code examples from the book and the implemented results.

Catalogue

• Result / ? Operator
• Pseudo-random number generator
• Parsing the command line

? Operator / Result

Further information | Rust Doc

fn main() -> Result<(), usize> {
    let array = [12, 19, 27];
    let found = array.binary_search(&19)?;
    println!("Found {}", found);
    let found = array.binary_search(&20)?;
    println!("Found {}", found);
    Ok(())
}

Pseudo-random number generators

main.rs

// Declare basic functions for pseudo-random number generators.
use rand::prelude::*;
fn main() {
    // Create a pseudo-Random Number Generator for the current thread
    let mut rng = thread_rng();
    // Print an integer number
    // between 0 (included) and 20 (excluded).
    println!("{}", rng.gen_range(0, 20));
    // Print a floating-point number
    // between 0 (included) and 1 (excluded).
    println!("{}", rng.gen::<f64>());
    // Generate a Boolean.
    println!("{}", if rng.gen() { "Heads" } else { "Tails" });
}

Cargo.toml

[package]
name = "use_rand"
version = "0.1.0"
authors = []
edition = "2018"

[dependencies]
rand = "0.6"

Parsing the command line

main.rs

use std::path::PathBuf;
use structopt::StructOpt;

#[derive(StructOpt, Debug)]
struct Opt {
    /// Activate verbose mode
    #[structopt(short = "v", long = "verbose")]
    verbose: bool,

    /// File to generate
    #[structopt(short = "r", long = "result", parse(from_os_str))]
    result_file: PathBuf,

    /// Files to process
    #[structopt(name = "FILE", parse(from_os_str))]
    files: Vec<PathBuf>,
}

fn main() {
    println!("{:#?}", Opt::from_args());
}

Cargo.toml

[package]
name = "use_structopt"
version = "0.1.0"
authors = ["carlomilanesi"]
edition = "2018"

[dependencies]
structopt = "0.2"

Type this in terminal

cargo run input1.txt input2.txt -v --result

Result

Result

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