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OK, so how can I code this up? Well, you might think, let's just jump in and write some code, I don't want to quite do that though, because I want to show you another tool that's valuable for thinking about how to structure the code, and that is a something called a flow chart. Now.
好，那么我怎么把这个以代码实现呢，你可能会想，让我们进去直接写代码把,但是我不想这么做，因为我想教给大家另外一项很有价值的,用来组织代码的工具，叫做流程图,现在，像Guttag教授,和我这么大岁数的人。
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Suppose I want to do little piece of code that's going to do planar geometry, points in the plane.
好，因此我需要一些,把这些东西收集到，一起的一些方式。
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And notice because I have just one line of code inside of each of these branches, what have I clearly omitted?
请注意因为我在每个分支中只有一行代码,显然地我省略了什么？
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And the most important thing in the Southern code of honor, I think, safe to say, was reputation.
南方人所谓的荣誉的核心部分,我以为,可以肯定的说,是声誉
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I'm not going to do it for you, but what would I think about doing when I change the code?
要改变代码应该做什么呢？,我不会帮你们做这些,但是我在改编代码的时候会想什么呢？
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Right now, I have to take that piece of code and replicate it everywhere I want in my larger file.
现在我要把这段代码,复制到,大文件中的各个部分。
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I will be posting code that you can play with, and I suggest you go through exactly this kind of exercise.
我给你一些你用的上的代码，我建议你们,多进行一些这种实验。
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But there's a key line of code that I lost over a moment ago and that was this one here.
但是我刚才漏了一行关键的代码,就是这里的这一行。
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Having now used this pseudo code to line things up, I can start putting some additional structure on this.
用伪代码把这些事情串起来后,我可以开始进行,一些结构方面的优化了。
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Because I might have written some code in which I'm expecting that integer particular variable to have an integer value.
因为我可能写了一些代码,来把一些,变量的类型，指定为。
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That is if I can write code that would solve all instances of smaller size strings, then what I just described isPalindrome will solve the larger size one.
然后我会描述如何处理大字符串,事实上这正是我所做的，我希望你能看看这边的这段代码,就是这个。
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I want the function, which is a little tool, a line of code I can include in my own programs and generally those tools live in sections two or three of the manual.
我想要一个函数，那是一个小工具，在我程序中可以包含的一行代码,通常这些工具在手册的第二节,或第三节。
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Up on the screen, I've got-- I commented it out, but I've got a piece of code that you've seen before, right up here. OK?
我现在在大屏幕上标出来的,是你们以前看过的一段代码,就在这儿？
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I want to show you how easy it is to change the code. But, notice, once I've added this I actually have a problem. This is now an under-constrained problem. I have more unknowns than I have equations.
我加上这个条件后,我马上面临一个问题了,这就是现在是一个非约束性问题了,我的未知数比方程数多,你从代数中可以知道。
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And for reference, incidentally, in case you ever forget what the point of some exercise was, I'll almost always comment the code up top with a quick sentence or two that reminds you what this program does.
顺便作为参考，为了避免我们可能忘记一些代码的意思，我通常会用一两个简单的句子,在上面作出注释,那样会提醒我们这个程序是干嘛的。
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If somewhere later on in the code it shifts to string, I might not be manipulating that and getting actual values out, but not what I wanted, and it's going to be really hard for me to chase it back.
然后后面的一些代码,把变量类型变为了字符串，我可能不会通过实际操作,去取得实际的变量的类型，但是这并不是我想要的类型,而且对我来说把类型，变回去也很困难。
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All right so-- yeah, how do I get to the code for that? That's interesting.
噢，我是怎么写出这个的代码,这件事儿挺有意思的。
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All right. The fourth thing I'm going to do, is I'm going to then construct the block of code.
好，我要做的第四件事情就是，我会去写这块循环代码。
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But if I did have two lines of code or more, I would in fact need to put those back.
但是如果我的确有两行或更多的代码，我其实应该把花括号加上。
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And then what I get to do inside the curly braces is literally line by line enumerate the cases that I want to apply to the following code.
然后我们在花括号中要做的是,逐行地列举接下来我想要,应用的代码。
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And we hope that at the end of the class, every time you're confronted with some technical problem, one of your first instincts is going to be, "How do I write the piece of code that's going to help me solve that?"
并且我们希望到了期末，每当你要面对一些,技术问题的时候，你们的本能之一将会是：,“我怎么才能编写一个代码,来帮我解决这问题？“
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I'm thinking about a problem, I'm going to show you an example in a second, first thing I'm going to do is say, what is the thing that's going to change every time I run through the same set of code?
我要解决一个问题，我马上会让大家看一个例子，第一件我要做的事情就是,弄明白每次运行同样的指令集时,每次都会改变的东西是什么？
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What does that say? It says if in the code up here I get an exception of that sort, I'm going to go to this place to handle it.
这意味着如果在代码中,我得到一个这样的异常,我能到这里来处理它。
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And I want to remind you, that block of code is a set of instructions, the same set of instructions that are going to be done each time through the loop.
我想提醒大家,这块代码是一个指令集,一个每次循环都会被执行的相同指令集,会变化的仅仅是变量的值。
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Which is a way of reminding you that I need to think as I write the code about what are my expectations from the input, and how might I enforce them.
通过这个我在提醒大家,在写代码的时候,要搞清楚对输入的期望，并思考下如何执行这些期望。
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The only thing I've done in this part of the program, now I'm going to go and read the code, is I've gotten the user to input a bunch of data.
现在我去读读这里的代码,是我会让用户输入一些数据，然后根据用户输入的数据。
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Now you have a set of parentheses as we'll see int i=0 in actual code and then I have int I equal 0.
你将会在实际的代码中看到一对圆括号,比如，我们让。
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Important lesson, so that there would be some predictability in the results and I would have some, if you will, smoke test for knowing whether or not I was getting, my code seemed to be working.
这很重要，因为这样我就可以预测,结果会是多少了，如果你愿意，我们可以做烟气试验,来看我的代码是否工作正常。
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And that then let's me get to, basically, base this code. Having done that, height I simply call base with get float, I call height with get float, and do the rest of the work.
现在让我们看看这段代码，其实已经写好了，我简单的调用下，用来得到一个浮点数，再调用下，来得到另外一个浮点数，然后做剩下的工作就可以了。
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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。
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