But when you start writing programs, especially when we get to web-based stuff where you want -- to check the user's input -- is it valid, is it an email address, -- and all these different scenarios -- it's actually often useful to be able to just enumerate them or rattle them off using this switching construct instead.

但是当你看是写程序时，特别是当我们,使用基于网络的东西，你想要,检查用户的输入-,它是合法的吗？它是不是一个电子邮箱地址？,所有的这些场景-,实际上它常常是有用的，当你用枚举结构列举它们,或者用它来快速地来说出它们。

哈佛公开课 - 计算机科学课程节选

And this is now a program that's web based, it's SMS based, it's voice based and it used to be Linux based as you'll see in a couple of weeks and it's just a program thatlet's you click where you are, click where you wanna go and voila, here are the next several shuttles that you can take.

这个程序现在是可以用网络访问的，可以用SMS的，可以用语音访问的,而且它曾经是Linux下的程序,你们几周后就会看到，它是这么一个程序,你可以点击确认你现在的位置,然后点你想要去的位置,然后程序会返回给你你能做的班车。

哈佛公开课 - 计算机科学课程节选