写入文件

use std::env;
use std::fs::File;
use std::io::Write;

fn main() {
    // Create a temporary file.
    let temp_directory = env::temp_dir();
    let temp_file = temp_directory.join("file");

    // Open a file in write-only (ignoring errors).
    // This creates the file if it does not exist (and empty the file if it exists).
    let mut file = File::create(temp_file).unwrap();

    // Write a &str in the file (ignoring the result).
    writeln!(&mut file, "Hello World!").unwrap();

    // Write a byte string.
    file.write(b"Bytes\n").unwrap();
}