Name: なぜCなのか？- CS50ポッドキャスト、第7話 (Why C? - CS50 Podcast, Ep. 7)
Uploaded: 2021-01-14T10:20:02.000Z
Duration: 35 min 40 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

My name is David Malan, and I'm here again with his CS50's own Brian Yu.

So CS50 is taught primarily in C, is the programming language that we teach

And a lot of students and people that we talk

to very often ask, why C, why is that the programming language

that you've chosen for CS50 as the language to start out with.

And I know that a couple of years ago you

answered a Quora post that was also asking the same question.

But I thought I'd take today as an opportunity on the podcast

to ask about that, push you a little bit on it,

and just discuss that, the pros and cons of the programming language

DAVID MALAN: Sure, in fact allow me to encourage folks to Google Quaro CS50

Why C, because, I daresay, it's a very thoughtful response out there

that actually took a couple hours to compose.

So I [INAUDIBLE] every point that I wanted us to hit.

Honestly, this is one of those religious questions even that comes up all

the time, especially when chatting with other teachers who teach computer

science who might be using Python or Java or C++ or C or something else.

It's kind of the go to language when you meet someone new in computer science

So I think it's only fair to disclaim that some of it

is probably my own upbringing when I took CS50 myself in 1996.

Professor Brian Kernighan was teaching the class year at Harvard.

And the course was under him and his predecessors

primarily in C. In fact, even more of the course was spent in C.

And so when I took the class, that was what I cut my own teeth on,

But with that said, with the benefit of hindsight, I do think pedagogically.

I have a more thoughtful answer these days, having now taught CS50 itself

and having deliberately chosen to stay with that language.

I think that it just has so many pedagogically upsides

despite some of its simultaneous pedagogically downsides.

And even within a handful of weeks in CS50,

can we expose students to most of the language.

We leave out just a few more advanced or more arcane

topics, like unions or function pointers,

and a couple of other syntactic features as well.

But by the end of the semester have students seen most of what

Two, it's about as close to the hardware as you

can get before you have to creep into what's called the assembly

language, which if you think C is scary, assembly language is

way scarier than that just syntactically and just how much control you,

the programmer, have to exercise over what's going on inside the machine.

That's a little too low level, I think, for students' first exposure

to programming, whether they're a major or nonmajor.

But I think it's also at the tail end of CS50, as time with C,

it's just so wonderfully empowering to go on one day from-- or one week

having implemented, say, your own hash table-- a particularly

sophisticated data structure in C-- and probably having spent hours

and hours getting that data structure to, not only be correct,

but to be performant as well, using as efficiently as possible

your computer CPU cycles and memory and then

the next week, literally-- at least in the way CS50

is structured-- to go to Python, for instance, most recently

reimplementing the entirety of that data structure

in just one line using a dictionary or dict in Python

And I think that really speaks to the takeaways of abstraction

that we want students to have in a course.

You understand the underlying implementation details.

Now I'm going to operate at and write code in a higher level of abstraction.

BRIAN YU: So you talk a lot about the pedagogically upsides of C.

What are the pedagogically downsides on the other hand?

DAVID MALAN: Yeah, pointers is probably the go to answer here.

With great power comes great responsibility.

And admittedly, we do have to delve or we choose to delve deeply into pointers

and memory management more generally, the upsides of which--

I think are that we can have even more interesting conversations

about security and the implications for management of one's own data

that you just can't have as effectively in higher level languages that

But the downside, pedagogically and just technologically,

is that students really do trip over their code

ever more so because in C, if unfamiliar,

you have the ability to actually touch specific addresses and memories.

So if your program has the illusion of, say, 2 gigabytes of space,

you can touch every byte of memory there,

for better or for worse, even if you're not supposed to.

And the result of touching memory that you're not supposed to

is often what's called a seg fault or segmentation

fault or, more mechanically, just your program freezes or crashes

But I think that it gives you thereafter so much more

of an appreciation for what a computer or a language or a runtime

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なぜCなのか？- CS50ポッドキャスト、第7話 (Why C? - CS50 Podcast, Ep. 7)

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