>> [MUSIC PLAYING]

>> [音樂播放]

DAVID MALAN: All right.

DAVID馬蘭：好的。

This is CS50.

這是CS50。

[MUSIC PLAYING Tritonal, Cash Cash, "Untouchable"]

[音樂播放Tritonal，現金現金，  “賤民”]

[MUSIC PLAYING]

[音樂播放]

SPEAKER 1: I'm going to France, and you're going, too.

揚聲器1：我要去 法國和你要去了。

[MUSIC PLAYING]

[音樂播放]

DAVID MALAN: This is CS50, Harvard University's introduction

DAVID馬蘭：這是CS50， 哈佛大學的介紹

to the intellectual enterprises of computer science

以智力 計算機科學的企業

and the arts of program-- and for the first time in history,

和program--的藝術 對於在歷史上第一次，

Yale University's as well.

耶魯大學也是如此。

Indeed, whether you're here in Cambridge or in New Haven or Miami or St. Louis

事實上，無論你在這裡在劍橋 或在紐黑文和邁阿密或聖路易斯

or Amsterdam or anywhere around the world

或阿姆斯特丹或任何地方 世界各地的

taking CS50, computer science E50, CS50X, CS50 AP,

服用CS50，計算機 科學E50，CS50X，CS50 AP，

we are all one and the same.

大家都是同一個。

Welcome to CS50.

歡迎CS50。

>> What we have--

>> 我們have--

>> [APPLAUSE]

>> [掌聲]

>> [LAUGHS]

>> （笑）

>> [APPLAUSE]

>> [掌聲]

>> So I made a mistake myself some time ago when I started off college.

>> 所以，我犯了一個錯誤我自己的一些 很久以前，當我開始上大學。

And I got to college, and I decided to frankly, stick within my comfort zone.

而我上大學，我決定 坦率地說，堅持在自己的安樂窩。

I ended up declaring a concentration, or a major, of government.

最後我聲明濃度， 或重大的政府。

Ant that was mostly a function of me being pretty familiar with government

螞蟻主要是我的函數 是非常熟悉政府

or at least history or I really liked constitutional law in high school.

或者至少是歷史還是我真的很喜歡 憲法在高中。

And so when I got here, I kind of gravitated toward things

因此，當我來到這裡，我種 的趨向了往東西

with which I was already familiar.

與我已經熟悉了。

Right?

對嗎？

God forbid I do poorly in the class.

上帝保佑我在課堂上做的很差。

I certainly wanted to stay within my comfort zone,

我當然想留 在我的安樂窩，

and it wasn't until sophomore year that I finally

而且直到 大二那年，我終於

got up the nerve to step foot in a classroom called CS50.

鼓起勇氣步驟腳 在一個名為CS50教室。

And at that point, did I finally realize that, my God, homework could actually

在這一點上，我才終於明白 是，我的上帝，家庭作業居然可以

be fun.

很有趣。

>> Indeed, I was one of those kids that on Friday evenings when

>> 事實上，我是那種一個孩子 上週五晚上，當

the P-SETS would be released, I would go back to my room and dive

在P-SETS將被釋放，我 會回到我的房間，潛水

into the night's P-SETS.

到晚上的P-集。

And for me, that was a sign that this was a field for me.

而對於我來說，這是個好兆頭 這是一個場對我來說。

But what was more important was the fact that I did get up this nerve

但更重要的是 事實上，我的確得到了這根神經

to explore waters unfamiliar to me and get beyond my own comfort zone

探索對我不熟悉的水域 並獲得超出了我自己的安樂窩

and frankly, I only was able to do that sophomore year by taking this class

坦率地說，我只能夠做到這一點 大二的時候採取這一類

pass/fail.

通過/失敗。

>> Indeed, it was the very last day that I finally switched over and finally

>> 事實上，這是最後一天， 我終於切換，最後

declared CS as my concentration, putting gov at that point behind me.

聲明CS為我的注意力， 把政府網站在我身後這一點。

And so we're not setting out in this course to turn all of you

所以，我們不設置在 這當然把所有你

into CS majors or concentrators, but rather to give you an opportunity

進入計算機專業或集中，但 而是為了給你一個機會

to hopefully go beyond the world with which you're currently familiar

有希望超越世界 與您目前熟悉

and bring back from this world skills and knowledge and savvy

而從這個世界帶回 技能和知識和悟性

that you can apply to your own world, whether that's

您可以應用到您的 自己的世界，不管是

in the humanities, social sciences, natural sciences, or beyond.

在人文科學，社會科學， 自然科學，或超越。

>> Indeed, if you're feeling a little intrepid

>> 事實上，如果你 感覺有點勇敢

about being in this room let alone in this class,

關於這個房間是 更何況在這個班，

realize that if history is any indication, 72% of you

認識到，如果歷史 任何跡象表明，你72％

have never taken a CS course before.

以前從來沒有採取CS課程。

So it is by all means not the case that the student sitting to the left

因此，它是通過各種手段並非如此 該學生坐在左邊

or to the right or in front or behind you knows far more about CS

或向右或前面或 你身後知道遠更多關於CS

or programming in particular than you.

或在特定的比你的編程。

That's not in fact the case.

這其實不是這樣的。

And indeed, much of the support structure

事實上很多， 支撐結構

that we've set up in this course over the past many years

我們已經在此設立 當然，在過去的許多年

has been for exactly that reason-- to provide an on ramp that still exits

一直正是reason--到 斜坡上仍然退出提供

just as rigorously and just as high as ever--

正如嚴格和 一樣高ever--

but the slope of which allow students less comfortable and more comfortable

但它的坡度讓學生 那麼舒服，更舒適

alike to succeed irrespective of his or her prior background.

一樣的成功，不論 他或她事先背景。

>> Indeed, what ultimately matters in this class is not

>> 的確，最終 問題在這個類是不

so much where you end up relative to your classmates

這麼多，你最終會 相對於你的同學

but where you in week 12 end up relative to yourself

但如果你十二週 結束了相對於自己

in week zero, which is where we are here today.

在零週，這是 我們今天在這裡。

>> Indeed and this may very well and probably does look like Greek

>> 事實上，這可能非常好 而且很可能看起來像希臘

to many of you.

許多你。

But rest assured, that this and so much more

不過放心，這 這和這麼多

is going to be completely within your grasp in just a little bit of time.

將是完全在你的 把握時間只是一點點。

>> But today, we focus on some of the higher level ideas

>> 但是今天，我們關注一些 的較高級別的想法

to give you a taste of CS50 and computer science

給你的味道 CS50和計算機科學

in a sense of what you're signing up for.

在某種意義上是什麼 你報名參加。

And indeed, computer science might be distilled more

事實上，計算機科學 可能更蒸餾

simply as computational thinking-- thinking like a computer, if you will.

簡單地計算thinking-- 思就像一台電腦，如果你願意。

And there's so many different things ingredients that go into that,

而且有這麼多不同的事情 成分進入的，

but let's propose just three for today.

但是讓我們提出只有三個為今天。

If the goal of the class ultimately is not to teach you programming,

如果類的目標，最終 不是教你編程，

is not to teach you C or PHP or SQL or any number of the words

是不是要教你C或PHP或 SQL或任何數目的字

and acronyms in the course's description,

並在縮略語 當然描述，

but rather to teach you to solve problems more effectively

而是教你 更有效地解決問題

and to think more methodically and more algorithmically, so to speak.

並認為更有條理和 更多的算法，可以這麼說。

Let's see what exactly this means.

讓我們來看看究竟是什麼意思。

>> So I would propose that thinking computationally boils down

>> 所以，我建議思考 計算歸結

to solving problems.

以解決問題。

What do you need to solve a problem?

你有什麼需要解決的一個問題？

You need to input-- like the input to the problem--

您需要input--像 輸入到problem--

you need an output, which is hopefully the solution,

需要的輸出，這 是有希望的解決方案，

and then you need a process by which to solve that problem, which

然後你需要一個過程， 要解決這個問題，這

we'll call an algorithm-- a set of instructions for solving some problem.

我們會打電話給一個算法 - 一組 說明解決一些問題。

>> But first, let's focus on the first and the last of these inputs and outputs.

>> 但首先，讓我們關注的第一和 最後這些輸入和輸出。

Computers after all, apparently only understands zeros and ones.

計算機畢竟，顯然 只有理解零和一。

But how can that possibly be?

但如何才能使這可能是？

Even if you're not familiar at all with what's underneath the hood,

即使你不熟悉的一切 什麼是引擎蓋下，

you probably at least heard that computers understand binary--

你可能至少聽說 計算機能夠理解binary--

just zeros and ones-- but how can you possibly do anything interesting?

只是零和ones--卻怎麼也 你可能做什麼有趣的事？

>> Well, one of the themes of the class is going

>> 好了，主題之一 類的會

to be this layering-- where today, we'll take a quick glance at the lowest level

是這個layering--今天在這裡，我們將 我們快速瀏覽一下的最低水平。

details, but with each passing day, where we layer

細節，但與每 過一天，我們在那裡層

or abstract on top of those details to actually solve higher level

或者在這些細節上面抽象 要真正解決更高層次

problems of interest to us.

我們感興趣的問題。

>> So here is what we might call binary-- with just an alphabet of 0 and 1.

>> 因此，這裡就是我們可以稱之為binary-- 用0和1只是一個字母。

But we humans are mostly familiar with decimal.

但是，我們人類大多 熟悉小數。

Dec meaning 10.

十二月意義10。

Bi meaning two.

畢意兩種。

And so in the decimal system, we have 10 digits

並因此在小數 系統，我們有10位

at our disposal-- of course, zero through nine.

在我們的disposal-- 當然，0到9。

So if you look at a number like this, most of you

所以，如果你看一個數字 像這樣的，你最多

intuitively just grasp that is 123.

直觀地只是把握是123。

There's nothing really hard about that.

沒有什麼真的很難有關。

But why is it 123?

但為什麼123？

Well, if you think back to grade school-- or at least

好吧，如果你想回 等級school--或至少

the way I learned this kind of world-- you

我了解到這個問題的方法 那種天下 - 你

might recall that we treated these things in columns, or places.

可能還記得，我們​​處理這些 事情列或場所。

>> So we have the ones place on the right.

>> 因此，我們有在右側的那些地方。

The tens place in the middle.

十位放置在中間。

The hundreds place on the left.

數百放置在左側。

And then how do we get from this pattern symbols--

然後我們怎麼 從這種模式symbols--

1 2 3-- to this higher level idea that we know as 123?

1 2 3--至更高水平 想法，我們所知道的123？

Well, it's just some simple arithmetic.

好吧，這只是一些簡單的算術。

Right?

對嗎？

>> The one there is essentially means give us 100 times 1 plus 10 times

>> 一個有實質上是指 給我們100倍1加10倍

2 plus 1 times 3.

2加1次3。

And of course if we do out the math there, it's 100 plus 20

當然，如果我們做出來的 數學那裡，它是100加20

plus 3-- otherwise known as 123.

加3--否則稱為123。

>> So if you're on the same page as that right

>> 所以，如果你在 同一個頁面的右側

now and are comfortable with the so-called decimal system as a human,

現在是舒服的 所謂十進制系統作為一個人，

it's actually well within your scope of comfort

它實際上完全在 您的舒適範圍

to consider now the binary system.

現在要考慮的雙星系統。

Take a wild guess-- this represents, in the world of computers

以野生guess--這代表， 在計算機的世界

in binary-- what number?

在binary--什麼號碼？

Zero.

零。

>> But why is that?

>> 但是，這是為什麼？

Well, it turns out that the columns or places here-- they're not powers of 10.

嗯，事實證明，該列或 這裡 - 他們不是10的冪的地方。

1, 10, 100, 1,000, and so forth.

1，10，100，1000，等等。

They're instead, quite simply, powers of 2.

他們相反，相當 簡單地說，2的冪。

So, 1, 2, 4, 8, 16, 32, and so on.

因此，1，2，4，8，16，32，等等。

And so now we of course get to 0 here simply because we have 4 times

所以，現在我們當然得到0 在這裡，只是因為我們有4倍

0 plus 2 times 0 plus 1 times 0, which of course gives us 0.

0加2次0加1次 0，這當然給了我們0。

>> But how do I go about representing the number 1?

>> 但我怎麼去 表示數字1？

What's the pattern of zeros and ones to represent

什麼是模式 零和一表示

the number we humans know as 1?

數我們人類所知道的1？

001.

001。

And 2?

和2？

010.

010。

>> And now the pattern starts to repeats.

>> 而現在的模式開始重複。

Now it's 011.

現在是011。

And again, 0 fours, one 2, one 1.

再次，0四肢一2一1。

So 2 plus 1.

因此，2加1。

That's 3.

這是3。

>> And now to represent 4, we don't just change that 0 to a 1.

>> 現在來表示4，我們 不只是改變0到1。

You sort of have to carry, so to speak, and the numbers

那種你必須隨身攜帶， 可以這麼說，而且數量

start flipping around just like in the decimal world.

開始只是翻轉各地 像在十進制世界。

>> So this is 4.

>> 因此，這是4。

This is 5.

這是5。

This is 6.

這是6。

This is 7.

這是7。

And so we've counted as high as 7.

所以，我們計算高達7。

>> Now all we just need is more a bits-- more zero's and one's.

>> 現在我們只是需要更多的是 bits--更多的零的和一個人的。

And indeed "bits", if you've heard this term-- binary digit.

事實上“位”，如果你 聽到這個term--二進制數字。

Bit is where that comes from.

位就是來自。

And so if we want to represent bigger numbers, we need more bits.

所以，如果我們要代表 更大的數字，我們需要更多的位。

But let's move away from slides now to something a little more real.

但是，讓我們遠離幻燈片現在 以一些更實際。

Suppose that we want to actually represent this thing.

假設我們要 實際上代表這件事情。

>> Well let's take a look now at a little demonstration.

>> 那麼讓我們來看看現在 在一個小演示。

So this is a web based application that one of CS50's own, Michael G,

因此，這是一個基於Web的應用程序 這對CS50自己，邁克爾·摹之一，

put together this summer to help us elucidate exactly this idea.

放在一起在今年夏天幫助 我們闡明正是這種想法。

And would someone like to venture up on stage

並會有人喜歡 冒險在舞台上

in front of all his or her classmates?

在他或她的所有同學面前？

Right there in front.

正確的，在前面。

Come on up.

上來吧。

>> You have to be comfortable on camera and the internet.

>> 你必須要舒服 在相機和互聯網。

Oh, right here.

呵呵，就在這裡。

OK.

確定。

We're OK.

我們很確定。

All right.

好的。

Come on up.

上來吧。

What's your name?

你叫什麼名字？

Emily come on up.

艾米麗上來吧。

So this is Emily.

因此，這是艾米莉。

What year are you?

哪一年是嗎？

>> Freshman.

>> 大一。

>> Emily, nice to meet you.

>> 艾米麗，很高興見到你。

David.

大衛。

>> All right.

>> 好的。

So up on the screen here, we have this touch screen

因此，在屏幕在這裡， 我們有這樣的觸摸屏

which is going to allow us to actually interact with this program,

這將允許我們 這個程序實際上是互動，

and it's just a browser.

它只是一個瀏覽器。

It's Chrome full screened at the moment, but it's

它的鍍鉻全屏蔽 此刻，但它的

been programmed by Michael to respond in a way that allows

已編程邁克爾 的方式，允許響應

us to play around with binary digits.

我們玩的二進制數字。

>> So for instance, here we have not three but eight bits-- zeros and ones.

>> 因此，例如，我們在這裡有沒有 3條，但8 bits--零和一。

Right now, we're looking at the number 0.

現在，我們 看數字0。

And indeed, all eight zeros in decimal means zero.

事實上，所有八個零 十進制表示零。

So that's all that's being hinted at here.

所以，這一切的 被暗示在這裡。

>> So if you wanted to represent the number 8,

>> 所以，如果你想 表示數字8，

what's the pattern of zeros and ones that you want?

什麼是零的格局 和那些你想要什麼？

You can simply tap up or down or the numbers themselves.

你可以簡單地點擊向上或向下 或數字本身。

All right.

好的。

So that of course is 8, as you can see up there.

使當然是8， 你可以看到在那裡。

And if we wanted to do 16, what do we do?

如果我們想 做16個，我們該怎麼辦？

>> Yep, just touch it again.

>> 是的，只需再次觸摸它。

16.

16。

All right.

好的。

So this is all fine and good, it's still very low level.

因此，這是一切優秀和良好， 它仍然是非常低的水平。

We need a way in the real world for Emily

我們需要的一個方式 現實世界中的埃米莉

of actually representing these things.

實際上代表這些東西。

And so suppose that we turn these zeros and ones, which is very

所以，假設我們把這些 零和一，這是非常

conceptual, into actual light bulbs.

概念，為實際燈泡。

Right?

對嗎？

>> A computer is a physical, mechanical, electrical device.

>> 計算機是一種物理， 機械，電氣設備。

And its input-- at least if you plug it in or charge it--

和至少如果其input-- 您或負責將其插入它 -

is to have battery power and electrons flowing in and out.

是有電池電量和 電子流進和流出。

>> So now, why don't we stop thinking about bits as zeros and ones,

>> 所以，現在，我們為什麼不停止思考 關於位為0和1

but something more physical like light bulbs here.

但更多的東西物理 就像燈泡在這裡。

And if Dan Armendariz could join me for just a moment-- come on up--

如果丹Armendariz環能加盟 我只是一個moment--來吧up--

we're going to queue up an application.

我們要排隊的應用程序。

>> Come on over, Emily.

>> 你過來吧，艾米麗。

Sorry this is the most awkward demo for you ever.

很抱歉，這是最 尷尬的演示給你直到永遠。

Come on over here.

來吧，在這裡。

We're going to queue up with thanks to Dan

我們要排隊 與感謝Dan

Armendariz, another member of our staff, an application known as binary bulb.

Armendariz環，我們的工作人員的另一名成員， 稱為二進制燈泡的應用程序。

>> So what we have here is an iPad application

>> 所以，我們在這裡 是一個iPad應用程序

that has the following user interface on the screen for Emily.

具有以下用戶 界面屏幕艾米麗上。

It's just got the same exact UI essentially that's over there.

這只是得到了完全相同的用戶界面 基本上是在那邊。

And if you now want to represent the number, say 8,