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It's one thing to plug in all the numbers and say, "I know Newton's laws and I know how they work."
我们平时只是把数字代进公式,然后说,"我懂牛顿定律,也知道怎么使用"
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And then that one's got an 18 on it, so I had it for like two years now.
然后那个上面有一个数字18，所以我拥有它两年了。
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So what would I want to do? I'd like to somehow walk down each of the digits one at a time and add them up. Ah, that's a looping mechanism, right? I need to have some way of walking through them.
去取这个数的,每个数字然后把他们加起来,啊，这是个循环机制对不对？,我得找到一个遍历它们的方法,一种简单的方法可能。
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You actually need to kind of do this and then you can swap these two numbers but it requires 50 percent more memory.
你实际上需要这样做,然后才能交换两个数字,但是它需要多50%的内存。
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So in that numbers game, the game when all of you wrote down a number and handed it in at the end of last time, the players were who? The players were you. You'all were the players.
在那个数字游戏中,你们每个人都写下了一个数字,然后在下课前交了上来,谁是参与人呢,你们就是参与人
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And, that gives you a number for the fluorine, minus 0.29. Now, if you do the same for the hydrogen, you'll come up with the same number.
然后给出F的数字，负的0。29，如果同样的用H来计算，你会得到一样的答案。
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Just two, I touched 6 once and then I moved ahead, and then I touched 8 and I moved ahead, not touching any other number.
只有2次，我先将6移了下来，然后将8移了下来，并没有动其他的数字。
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And if you just look at the numbers, you can see how it cuts in from one side and then the other side as it keeps narrowing that range until it gets down to the place where there are at most two things left, and then it just has to check those two to say whether it's there or not.
你能看到他是如何不断的，从一个大的范围被拦腰劈开,知道最终只剩下两个数字,然后就只需要,比一比就知道结果了,将它同线性查找比较下。
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It's a secret number so that if Julius Caesar scrambled his message with the key 13, well, then the recipient had better know what that number is or realistically, -- and this is why it's kind of hard to buy -- into some of these age old algorithms, -- what would an alternative approach be to figuring out Julius Caesar's messages to his generals if he didn't know that secret number was 13?
它是一个机密的数字，以至于,如果凯撒大帝使用密钥13加密了它的消息，然后接收者最好知道那个数字是什么,实际上--这就是为什么很难,破解这些古老的算法-,有什么变换方法使凯撒大帝的将军,可以解密凯撒大帝的消息，如果他不知道,那个机密数字是13呢？
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We own our own phone number, that allows you to input key strokes like you would any system and this is an example of what we call CS50 Voice.
我们都有电话号码，这就让我们可以输入任意的数字,然后这是CS50，Voice的一个例子。
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You notice what it did, it printed out that little, right up here I'd said enter a number and that's what it's printed out, so I can enter a number and it prints it out.
注意这个程序做了些什么，显示出了指定值，然后显示需要输入个数字,然后程序会显示这个数字，我输入一个数字然后程序显示了它。
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3 >> Okay. I'll just go over here to y and get the number 13 set up and then take the wand of dereferencing and just, whoa.
>，好的，我将到y这里，然后存储数字,然后使用魔杖，哇哦。
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But there's an important thing going on here, if I in fact wanted to combine those into a string I should have told the machine to do that, and I can do that, by explicitly saying, take that, which is a number, then add it to that string.
但是这里有个很重要的事情，实际上想要把这些加到一个字符串里面去,我应该告诉计算机去做这个，我应该这么做，通过明确的输入，也就是把这个对象，一个数字，然后把它加到一个字符串里面去。
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