Rust by Example

create

The create static method opens a file in write-only mode. If the file already existed, the old content is destroyed. Otherwise, a new file is created.

static LOREM_IPSUM: &str =

"Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod

tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,

quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo

consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse

cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non

proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

";

use std::fs::File;

use std::io::prelude::*;

use std::path::Path;

fn main() {

let path = Path::new("lorem_ipsum.txt");

let display = path.display();

// Open a file in write-only mode, returns `io::Result`

let mut file = match File::create(&path) {

Err(why) => panic!("couldn't create {}: {}", display, why),

Ok(file) => file,

};

// Write the `LOREM_IPSUM` string to `file`, returns `io::Result<()>`

match file.write_all(LOREM_IPSUM.as_bytes()) {

Err(why) => panic!("couldn't write to {}: {}", display, why),

Ok(_) => println!("successfully wrote to {}", display),

}

}

Here's the expected successful output:

$ rustc create.rs && ./create

successfully wrote to lorem_ipsum.txt

$ cat lorem_ipsum.txt

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod

tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,

quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo

consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse

cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non

proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

(As in the previous example, you are encouraged to test this example under failure conditions.)

There is OpenOptions struct that can be used to configure how a file is opened.