Improve std::fs::read_to_string example

[haydonryan]

Resolves #118621

For the original code to succeed it requires address.txt to contain a socketaddress, however it is much easier to follow if this is just any strong - eg address could be a street address or just text.

Also changed the variable name from "foo" to something more meaningful as cargo clippy warns you against using foo as a placeholder.

$ cat main.rs 
use std::fs;
use std::error::Error;

fn main() -> Result<(), Box<dyn Error>> {
    let addr: String = fs::read_to_string("address.txt")?.parse()?;
    println!("{}", addr);
    Ok(())
}

$ cat address.txt 
123 rusty lane
san francisco 94999

$ cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `/home/haydon/workspace/rust-test-pr/tester/target/debug/tester`
123 rusty lane
san francisco 94999

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[ilyvion]

read_to_string already returns Result<String>, you gain nothing by calling .parse()? here anymore now that the value isn't expected to be a SocketAddr or other parsed value.

[haydonryan]

Totally agree I'll update the pr.

[haydonryan]

I updated this and removed an unused import for read_from_string. EDIT: deleted that as it broke the build. In retrospect I think I probably should have reverted the offending commit. (Happy to take suggestions here)

I also added a commit that updated the fs::read documentation as that also used a SocketAddr (that resulted in an error).

[workingjubilee]

lgtm.

@bors r+

[bors]

📌 Commit b5e1ca3 has been approved by workingjubilee

It is now in the queue for this repository.