Standard Library - Misc

The standard library provides additional complex types to support things like:

• Threads
• Channels
• File I/O
• Program Arguments
• Foreign Function Interface

You can find enhanced alternatives for many of these by visiting crates.io. For example, clap is a popular crate for working with program arguments.

Learn more: https://doc.rust-lang.org/stable/rust-by-example/std_misc.html

File I/O - Open

use std::fs::File;
use std::io::prelude::*;
use std::path::Path;

fn main() {
    // Create a path to the desired file
    let path = Path::new("hello.txt");
    let display = path.display();

    // Open the path in read-only mode, returns `io::Result<File>`
    let mut file = match File::open(&path) {
        Err(why) => panic!("couldn't open {}: {}", display, why),
        Ok(file) => file,
    };

    // Read the file contents into a string, returns `io::Result<usize>`
    let mut s = String::new();
    match file.read_to_string(&mut s) {
        Err(why) => panic!("couldn't read {}: {}", display, why),
        Ok(_) => print!("{} contains:\n{}", display, s),
    }

    // `file` goes out of scope, and the "hello.txt" file gets closed
}

(Code example is copied directly from here.)