More idiomatic retrieval of command-line args

[skade]

The current slides use this code:

fn main() {
    let args: Vec<String> = env::args().collect();

    if args.len() > 1 {
        println!("{}", match read_file(args[1].clone()) {
            Ok(content) => content,
            Err(reason) => panic!(reason) 
        });
    }
}

This does unnecessary bounds checking and an allocation of the command line args.

env::args() is an iterator and already provides positional and crash-safe access to command line arguments:

fn main() {
    let mut args = std::env::args();

    println!("{}", args.len());
    if let Some(file) = args.nth(1) {
        println!("{}", file);
    }
}

I think it would be better to use this. I'm also confused about the clone-call after args[1], is it related to args[1] returning a reference as opposed to the exact value?

[chikoski]

Thanks. The suggested code look like written in more Rust way. I will update my material with it. Also add a explanation of if let, which is a prerequisite to understand this code.