循环控制

Rust 中有三个循环关键字：while、loop 和 for：

while

The while keyword works much like in other languages, executing the loop body as long as the condition is true.

fn main() {
    let mut x = 200;
    while x >= 10 {
        x = x / 2;
    }
    println!("Final x: {x}");
}