以运行的多快，也是指编写 Rust 程序的速度。Rust 编译器的检查确保了增加功能和重构代码 时的稳定性，这与那些缺乏这些检查的语言中脆弱的祖传代码形成了鲜明对比，开发者往往不 敢去修改这些代码。通过追求零成本抽象（zero-cost abstractions）—— 将高级语言特性编 译成底层代码，并且与手写的代码运行速度同样快。Rust 努力确保代码又安全又快速。 这里提到的只是几个较大的受益群体，Rust 语言也希望能支持更多其他用户。总的来说， if number != 0 { println!("number was something other than zero"); } } 运行代码会打印出 number was something other than zero。 使用 else if 处理多重条件 可以将 else if 表达式与 if 和 else 组合来实现多重条件。例如： 文件名：src/main let contents = "\ Rust: safe, fast, productive. Pick three. Trust me."; assert_eq!( vec!["Rust:", "Trust me."], search_case_insensitive(query, contents)

until there is room for another item. A Queue maintains a count of unfinished tasks, which begins at zero. put increments the count; task_done decrements it. In the web-spider example here, the queue begins is also no work left in the queue. Thus that worker’s call to task_done decrements the counter to zero. The main coroutine, which is waiting for join, is unpaused and finishes. #!/usr/bin/env python3 touches the global IOLoop instance (even indirectly) before the fork. Second, it is difficult to do zero-downtime updates in this model. Finally, since all the processes share the same port it is more difficult

until there is room for another item. A Queue maintains a count of unfinished tasks, which begins at zero. put increments the count; task_done decrements it. In the web-spider example here, the queue begins is also no work left in the queue. Thus that worker’s call to task_done decrements the counter to zero. The main coroutine, which is waiting for join, is unpaused and finishes. #!/usr/bin/env python3 touches the global IOLoop instance (even indirectly) before the fork. Second, it is difficult to do zero-downtime updates in this model. Finally, since all the processes share the same port it is more difficult