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But if it is not, it's going to print out a message here saying, you screwed up, somewhat politely, and it's going to go back around. So it'll just cycle until I get something of the right type.
但是输入不是浮点数的话,我这里就会显示一个消息说，你搞砸了，该稍微有点礼貌吧？,然后我们继续执行循环,一直到得到正确类型的输入。
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OK, says it says enter a float. I give it something that can be converted into a float, it says fine. I'm going to go back and run it again though. If I run it again, it says enter a float.
好了，看到他说输入一个浮点数,我输入它可以转换为浮点数的值,那没问题，我回过来再运行一遍,如果我再运行一遍。
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So the take away is that if the user actually gives me two or three or four or whatever, this is this expression "is n less than 1" is going to evaluate to false if it's actually two or three or four or whatever.
所以先不管用户实际上给我,3，4还是其他数，这个表达式,“是否n小于1“将被评估为错误的,如果输入额是2，3，4或其它的数。
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I could generalize this pretty nicely. Imagine the same kind of idea where I want to simply say I want to take input of anything and try and see how to make sure I get the right kind of thing. I want to make it polymorphic.
对吧，我试着输入浮点数,我能更好的一般化它,想象下类似的想法，我需要输入些什么,然后看看输入的是否正确,我想使他更多元化些。
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Last thing to say is why would you want to have exceptions? Well, let's go back to that case of inputting a simple little floating point.
最后要讲的是为什么有异常处理？,回到输入一个简单的小浮点数的例子,如果我期望主要是。
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Need to get the base in. Second thing I want to do, I need to get the height, so I'm going to input a value for the height, also as a float, a floating point.
也就是输入底的值，第二件我想要做的，事情就是得到三角形的高,因此我会输入一个值作为三角形的高，同样也是一个浮点数。
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So if I were to solve this problem, here's the way I would do it. I would say, first thing I want to do, is I want to input a value for the base as a float.
如果我想要解决这个问题，这就是我要解决它的方式了，第一件我要做的事情就是要,输入一个浮点数作为三角形的底。
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ReadFloat We'll look at it in a second. Let me sort of set the stage up for this -- suppose I want to input -- I'm sorry I want you as a user to input a floating point number.
名字叫,我们来看一会，我先来设置下情景-,假设我想输入，抱歉,我希望你们作为用户来输入一个浮点数。
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And again, if I just run this, just to show that it's going to do the right thing, it says enter base, I'm obnoxious, it says oops, wasn't a float, so we'll be nice about it and I enter a height, and it prints out what I expected. I just concatenated those strings together, by the way, at the end.
我再来运行下看是不是做对了,提示输入底，噢，它提示说不是浮点数，我很高兴，然后我输入一个,浮点数作为高度显示结果和我预期的相同,顺便说一句,我只是在最后把这些字符串连接起来了。
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I can't rely on Professor Guttag if I give this- if this code to him, I can't rely on him to type in a float. Actually I can, because he's a smart guy, but in general, I can't rely on the user-- I wouldn't do it right to see if you did.
当Guttag使用这段代码的时候-,我不能相信他一定会输入一个浮点数,实际上我能因为他很聪明，但是总体上来讲，别相信用户一定会按照规则来-,我会故意做错来试试你的程序的。
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And then I run a loop in which I read something in, I check to see if it's the right type, if it is, I change that variable to say it's now the correct type, which means the next time through the loop, I'm going to say I'm all set and I'm going to bounce out.
因为我还没输入，然后我运行一个循环,循环内部我输入一些东西,然后看看是不是正确的类型,如果是的话我改变input，Ok为真，来证明输入数是正确的类型，这就意味着下一次运行这个循环的时候,就可以跳出循环继续执行了。
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Ah ha, it goes into that accept portion, prints out a message, and goes back around the while loop to say try again. And it's going to keep doing this until I give it something that does serve as a float.
他会说输入一个浮点数，啊哈，它就到了那段处理代码,打印出消息,然后回到while循环让我们再输一次,它会持续这么做直到它接受到一个浮点数。
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So we'll talk a bit more about this idea of functions today, but, get int, again, can think of it as a black box, whose purpose in life is to prompt the human for input and pester the human if he or she doesn't actually give it int, but then once it has that, has entered it from the user, it's quote unquote, returns it to you.
所以我们进今天将多讨论点这个函数的概念，但是，GetInt，我们可以把它当做一个黑盒子，它的唯一目的是提示人们来输入,并且如果他或她没有,给它int数，则会纠缠用户，但是一旦它得到了，用户输入的int数，对输入进行引用，返回给你。
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