Although the accepted answer is correct, it doesn’t cover the non-trivial case. To stream output and handle it manually, use Stdio::piped() and manually handle the .stdout property on the child returned from calling spawn, like this: use std::process::{Command, Stdio}; use std::path::Path; use std::io::{BufReader, BufRead}; pub fn exec_stream<P: AsRef<Path>>(binary: P, args: Vec<&’static str>) { let mut … Read more
It seems what you need is “slice patterns”: fn main() { let line = “127.0.0.1 1000 what!?”; let v = line.split_whitespace().take(3).collect::<Vec<&str>>(); if let [ip, port, msg] = &v[..] { println!(“{}:{} says ‘{}'”, ip, port, msg); } } Playground link Note the if let instead of plain let. Slice patterns are refutable, so we need to … Read more
You need to explicitly opt-in by placing #![feature(collections)] at the top of your crate’s root source file. Using a nightly compiler merely permits you to use unstable features, it doesn’t automatically enable them. See also this related SO question.
The std::fs::File provides a metadata method. It can be used with your my_file like this: my_file.metadata().unwrap().len();
Since Rust 1.6, Read::read_exact can be used to do this. If bytes_to_read is the number of bytes you need to read, possibly determined at runtime, and reader is the stream to read from: let mut buf = vec![0u8; bytes_to_read]; reader.read_exact(&mut buf)?; The part that wasn’t clear to me from the read_exact documentation was that the … Read more
Possible solutions to codepoint slicing I know I can use the chars() iterator and manually walk through the desired substring, but is there a more concise way? If you know the exact byte indices, you can slice a string: let text = “Hello привет”; println!(“{}”, &text[2..10]); This prints “llo пр”. So the problem is to … Read more
Here’s a Minimal, Reproducible Example that exhibits the same problem that you experienced. I created a C library exporting a simple addition function. I also created a Cargo project to use this function. dynlink/ ├── executable │ ├── build.rs │ ├── Cargo.lock │ ├── Cargo.toml │ └── src │ └── main.rs └── library ├── … Read more
The other answers are outdated. As of Rust 1.27, you can use HashMap::retain to keep only the elements you are interested in. You specify the elements to keep using a closure. x.retain(|_, v| *v != 0);
This can be done with the action attribute. If your field is a bool then by default the action selected is ArgAction::SetTrue. This is quite nice since you don’t need to set a value when you call the argument. It sets the value by default to true if used and false if not used when … Read more
As explained in the rand 0.5.0 docs, gen_ascii_chars is deprecated and you should use sample_iter(&Alphanumeric) instead. use rand::{distributions::Alphanumeric, Rng}; // 0.8 fn main() { let s: String = rand::thread_rng() .sample_iter(&Alphanumeric) .take(7) .map(char::from) .collect(); println!(“{}”, s); }