Rust 练习：求一组数的最大公约数

下面程序求解若干自然数的最大公约数，自然数放在命令行中输入，源代码如下：

use std::io::Write;
use std::str::FromStr;fn gcd(mut x: u64, mut y: u64) -> u64 {
    loop {
    if x == y {
     break; }if x > y {
     x = x - y； }if x < y {
     y = y - x； }}x
}fn main() {
    let mut numbers = Vec::new();for arg in std::env::args().skip(1){
    numbers.push(u64::from_str(&arg).expect("error parsing argment"));}if numbers.len() == 0 {
    writeln!(std::io::stderr(), "Usage: gcd Number ...").unwrap();std::process::exit(1);}let mut d = numbers[0];for m in &numbers[1..] {
    d = gcd(d, *m);}println!("The greatest common divisor of {:?} is {}", numbers, d);
}

运行一下，有如下结果：

$ cargo run  45 9 81 27Compiling testweb v0.1.0 (/home/yeping/testweb)Finished dev [unoptimized + debuginfo] target(s) in 0.31sRunning `/home/.../gcd 45 9 81 27`
The greatest common divisor of [45, 9, 81, 27] is 9