text stringlengths 1 81 | start float64 0 10.1k | duration float64 0 24.9 |
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>> But, ultimately, what you're
going to see within CS50 IDE | 902.4 | 3.15 |
is three distinct areas--
an area on the left where | 905.55 | 2.79 |
your files are going to be in the
cloud, an area on the top right | 908.34 | 4.264 |
where your code is going to be editable. | 912.604 | 1.666 |
You'll be able to open
individual tabs for any program | 914.27 | 2.38 |
that you write this semester inside
of that top right hand corner. | 916.65 | 3.02 |
And then most arcanely,
and yet powerfully, | 919.67 | 3.4 |
is going to be this thing at the
bottom known as a terminal window. | 923.07 | 3.54 |
>> This is an old school
Command Line Interface, | 926.61 | 2.84 |
or CLI, that allows
you to execute commands | 929.45 | 2.79 |
on the computer-- in this case,
the computer in the cloud-- | 932.24 | 3.02 |
to do things like compile your code
from source code to machine code, | 935.26 | 3.83 |
to run your programs, or to start your
web server, or to access your database, | 939.09 | 4.51 |
and any number of other techniques
that we'll start to use before long. | 943.6 | 3.854 |
But to get there, we're
going to actually have | 947.454 | 1.916 |
to go online and start playing. | 949.37 | 1.87 |
And to do that, let's first
start tinkering with main, | 951.24 | 3.159 |
and write the main part of a program. | 954.399 | 1.541 |
And let's use that function
printf, which we used earlier, | 955.94 | 3.23 |
simply to say something. | 959.17 | 1.88 |
>> So here I am already inside of CS50 IDE. | 961.05 | 3.86 |
I've logged in advance. | 964.91 | 1.02 |
And I full screened the window. | 965.93 | 1.43 |
And so, ultimately, you
too in coming problems | 967.36 | 2.31 |
will follow similar steps that
will provide online documentation. | 969.67 | 3.29 |
So you don't need to worry about
absorbing every little technical step | 972.96 | 3.4 |
that I do here today. | 976.36 | 1.37 |
>> But you'll get a screen like this. | 977.73 | 1.492 |
I happen to be in night mode. | 979.222 | 1.208 |
And you can brighten everything
up by disabling night mode. | 980.43 | 2.514 |
And at the end of the
day, you're going to see | 982.944 | 1.916 |
these three main areas-- the file
browser at left, the code tabs up top, | 984.86 | 5.23 |
and the terminal window at the bottom. | 990.09 | 2.34 |
>> Let me go ahead and
write my first program. | 992.43 | 2.46 |
I'm going to preemptively go to File,
Save, and save my file as hello.c. | 994.89 | 7.41 |
Indeed, by convention, any program we
write that's written in the C language | 1,002.3 | 4.55 |
should be named something
dot c, by convention. | 1,006.85 | 2.889 |
So I'm going to name it hello.c, because
I just want to say hello to the world. | 1,009.739 | 3.291 |
Now I'm going to zoom
out and click Save. | 1,013.03 | 1.79 |
And all I have here now is a tab
in which I can start writing code. | 1,014.82 | 3.36 |
>> This is not going to compile. | 1,018.18 | 1.31 |
This means nothing. | 1,019.49 | 0.81 |
And so even if I converted
this to zeros and ones, | 1,020.3 | 2.45 |
the CPU is going to have no
idea what's going around. | 1,022.75 | 2.64 |
But if I write lines that do match
up with C's conventions-- C being, | 1,025.39 | 8.78 |
again, this language-- with syntax like
this, printf hello world-- and I've | 1,034.17 | 5.98 |
gotten comfortable with
doing this over time. | 1,040.15 | 2.06 |
So I don't think I made
any typographical errors. | 1,042.21 | 2.3 |
>> But, invariably, the very first
time you do this, you will. | 1,044.51 | 3.4 |
And what I am about to do might very
well not work for you the first time. | 1,047.91 | 3.18 |
And that's perfectly OK,
because right now you | 1,051.09 | 2.52 |
might just see a whole lot of newness,
but over time once you get familiar | 1,053.61 | 4.052 |
with this environment, and
this language, and others, | 1,057.662 | 2.208 |
you'll start to see things that
are either correct or incorrect. | 1,059.87 | 2.5 |
>> And this is what the
teaching fellows and course | 1,062.37 | 1.999 |
assistants get so good at over time, is
spotting mistakes or bugs in your code. | 1,064.369 | 4.411 |
But I claim that there
are no bugs in this code. | 1,068.78 | 3.33 |
So I now want to run this program. | 1,072.11 | 1.88 |
>> Now on my own Mac or PC, I'm in
the habit of double clicking icons | 1,073.99 | 3.45 |
when I want to run some program. | 1,077.44 | 1.91 |
But that's not the model here. | 1,079.35 | 1.73 |
In this environment, which is CS50 IDE. | 1,081.08 | 3.49 |
We are using an operating
system called Linux. | 1,084.57 | 2.622 |
Linux is reminiscent of another
operating system, generally known | 1,087.192 | 2.708 |
as Unix. | 1,089.9 | 0.95 |
And Linux is particularly known for
having a Command Line Environment, CLI. | 1,090.85 | 5.49 |
Now, we're using a specific
flavor of Linux called Ubuntu. | 1,096.34 | 3.73 |
And Ubuntu is simply a
certain version of Linux. | 1,100.07 | 2.7 |
>> But these Linux's these days do actually
come with graphical user interfaces. | 1,102.77 | 5.13 |
And the one we happen to
be using here is web-based. | 1,107.9 | 2.46 |
So this might look even a
little different from something | 1,110.36 | 2.375 |
you yourself might have
seen or run in the past. | 1,112.735 | 2.575 |
>> So I'm going to go ahead
now and do the following. | 1,115.31 | 2.6 |
I've saved this file as hello.c. | 1,117.91 | 3.04 |
I'm going to go ahead and
type clanghello.c So Clang | 1,120.95 | 6.4 |
for the C language is a compiler. | 1,127.35 | 2.5 |
It's pre-installed in CS50 IDE. | 1,129.85 | 2.102 |
And you can absolutely download and
install this on your own Mac or PC. | 1,131.952 | 2.958 |
>> But, again, you wouldn't have all of
the pre-configuration done for you. | 1,134.91 | 3 |
So for now, I'm just
going to run clanghello.c. | 1,137.91 | 3.03 |
And now notice this syntax
here will eventually | 1,140.94 | 2.3 |
realize just means that I'm in a
folder or directory called Workspace. | 1,143.24 | 3.69 |
This dollar sign is just convention
for meaning, type your commands here. | 1,146.93 | 4.1 |
>> It's what's called a prompt, just
by convention is dollar sign. | 1,151.03 | 3.53 |
And if I go ahead now and click
Enter, nothing seems to have happened. | 1,154.56 | 4.57 |
But that's actually a good thing. | 1,159.13 | 1.8 |
The less that happens on
your screen, the more likely | 1,160.93 | 2.72 |
your code is to be correct,
at least syntactically. | 1,163.65 | 3.06 |
>> So if I want to run this
program, what do I do? | 1,166.71 | 2.41 |
Well, it turns out that the
default name by convention | 1,169.12 | 4.65 |
for programs when you don't specify a
name for your program is just a.out. | 1,173.77 | 5.084 |
And this syntax too, you'll
get familiar with before long. | 1,178.854 | 2.416 |
>> Dot slash just means, hey, CS50
IDE, run a program called a.out | 1,181.27 | 6.23 |
that's inside my current directory. | 1,187.5 | 1.9 |
That dot means the current directory. | 1,189.4 | 2.12 |
And we'll see what other such sequences
of characters means before long. | 1,191.52 | 3.52 |
>> So here we go, Enter, hello world. | 1,195.04 | 3.39 |
And you'll notice, that what happened? | 1,198.43 | 1.65 |
Not only did it print hello world. | 1,200.08 | 1.5 |
It also moved the
cursor to the next line. | 1,201.58 | 4.41 |
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