使用Rust从std输入中读取行

Question

嗨，我想能够读取一个文件，其中包含json行到一个rust应用程序像这样

$ cargo run < users.json

，然后作为迭代器读取这些行。到目前为止，我有这段代码，但我不希望文件硬编码，而是像上面的行一样管道到进程中。

use std::fs::File;
use std::io::{self, prelude::*, BufReader};

fn main() -> io::Result<()> {
let file = File::open("users.json")?;
let reader = BufReader::new(file);
for line in reader.lines() {

println!("{}", line);
}
Ok(())
}

我刚刚解决了这个问题

use std::io::{self, BufRead};
fn main() {
let stdin = io::stdin();
for line in stdin.lock().lines() {
println!("{}", line.unwrap());
}
}

Answer 1

cargo help run:

NAME
cargo-run - Run the current package
SYNOPSIS
cargo run [options] [-- args]
DESCRIPTION
Run a binary or example of the local package.
All the arguments following the two dashes (--) are passed to the binary to run. If you're passing arguments to both Cargo and the binary, the ones after -- go to the binary, the ones before go to Cargo.

传递参数的语法是:

cargo run -- foo bar baz

你可以这样访问这些值:

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

一个完整的最小示例是:

use std::env;
fn main() {
let args: Vec<String> = env::args().collect();
dbg!(&args);
}

运行cargo run -- users.json将导致:

$ cargo run -- users.json                                                                                                                                                                                                                       
Finished dev [unoptimized + debuginfo] target(s) in 0.00s
Running `target/debug/sandbox users.json`
[src/main.rs:5] &args = [
"target/debug/sandbox",
"users.json",
]

Answer 2

use std::io::{self, BufRead};
fn main() {
let stdin = io::stdin();
for line in stdin.lock().lines() {
println!("{}", line.unwrap());
}
}