你为什么下来这里?
Why don't you come down here too?
你为什么不进来喝点呢?
Why don't you come down here and get these stones off the track?
你为什么不下车到这里来,把轨道上的这些石头搬开?
You can come in and sit down if you want; there's some space down here.
你想听的话进来找地儿坐下;,这里仍有位子。
But notice what this does. The first thing it does is, it says, let's check and make sure x is greater than or equal to 0. If it isn't, notice what's going to happen. None of that block is going to get executed, and it's going to come down here and print out a useful piece of information, which says, hey, you gave me a negative number. I don't know how to do this.
做的是和以前一样的事情,但是注释它做了什么,第一件做的事情就是,程序说,要去检查并且确信x是大于等于0的,如果不是的话,请注意会发生什么,下面的代码都不会被执行,程序会到这里来然后显示一些有用的信息,信息会说,嘿,你给了我一个负数,我不知道该怎么弄这个了。
应用推荐