First of all, having read in that value, I can check to see, is it of the right type?

首先，读一下这个值，我们可以来检查看看是不是正确的类型？

麻省理工公开课 - 计算机科学及编程导论课程节选

The easy thing to do would be the following: start at the front end of the list, check the first element. If it's the thing I'm looking for, I'm done. It's there. If not, move on to the next element. And keep doing that.

从数组的第一个元素开始：,如果这是目标元素那么结束,如果不是的话就继续比较下面的元素，并一直这么比较下去,但如果，在某一点我发现我要寻找的数字。

麻省理工公开课 - 计算机科学及编程导论课程节选

If I come into this code, I'm going to check this branch first, if it's not true, ah, there's a return at the end of that branch. If it is true, I do that, and then I've got a second test. If it's true, return I return, otherwise a return.

但是如果我们看看这里,如果我看这段程序,我会先检查这一部分，如果它是假的，啊，这部分分支结尾有一个。

麻省理工公开课 - 计算机科学及编程导论课程节选

Well, now I go through code very much like what I did for max val in the first place. I check whether it's 0, et cetera, et cetera.

现在我会捋一遍代码,就像我之前捋maxval函数一样,我会检查它是不是0等等等等。

麻省理工公开课 - 计算机科学及编程导论课程节选

All right, we're-- well actually, I should say that better, we first check to see, is x 0 greater than or equal to zero, if it's not, then we come down here and we print something out, otherwise we run through a little loop to get the answer, and then we check it and we spit something out.

然后我们运行一个小循环,好了，我们现在来看看,如果x≥0或者x＜,我们看这儿,我们会输出一些内容,或者我们运行一个小循环来获取答案,然后我们检验一下，然后得到结果。

麻省理工公开课 - 计算机科学及编程导论课程节选

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。

麻省理工公开课 - 计算机科学及编程导论课程节选