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>> [MUSIC PLAYING]

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>> ZAMYLA CHAN: Hello, world.

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Let's make our first C program.

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>> To write our programs, we'll be
working in the CS50 Appliance.

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It's a virtual machine that runs a
computer inside your computer.

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>> This has a lot of benefits.

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For one, it's already set up with a lot
of tools and you'll need for CS50.

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It also means that whether you have Mac,
PC, Linux, everyone's using the

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same thing.

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If you haven't downloaded the
CS50 Appliance yet, go to

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manual.cs50.net/appliance.

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>> I have my Appliance here full screen,
but you can also have it as a floating

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window, if you wish.

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I highly encourage setting up a dropbox
account for all of your CS50

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course work.

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That way, in case something happens with
your computer or the Appliance,

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you have a backup in the cloud.

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>> Let's open our terminal first.

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The terminal is an interface that we
can use to navigate around our

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computer, write, compile,
and run code.

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We'll actually write most of
our code in gedit, though.

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>> So let's bring this up now.

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It'll bring us to an unsaved document.

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Notice that I start typing my C code--

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there isn't any syntax highlighting.

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Syntax highlighting helps us visually by
coloring data types, functions, and

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variables differently.

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>> So let's save this program into
a folder, and call it hello.c.

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This way, we'll have syntax
highlighting as we type.

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We'll start by including
two libraries--

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include cs50.h and include stdio.h.

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This way, our program will have access
to the functions inside the CS50

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Standard I/O library.

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>> Each program needs a main function,
so let's write that here--

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main(void) with two curly braces.

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And now here is where you'll
write your program.

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>> For our first program, we'll just have
one line printf, hello, world!

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With a new line right
here for aesthetics.

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>> Once I save, I want to run my program.

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So I'm going to open my terminal now.

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I start go out in my home directory, but
to access hello.c, I need to be in

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the same directory or folder.

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So at this prompt right here,
I'm going to type cd--

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change directory--

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Dropbox/2013/walkthroughs.

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And now I'm in my walkthroughs folder.

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>> Say I forget what my
folders are called.

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Then I'll type ls, which will
list all of the files in

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this current directory.

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So changing directories a few
times more, I find hello.c.

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And this process is analogous to
navigating through Finder on Macs or

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My Computer in Windows.

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In fact, I can even make folders or
directories right from the terminal

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with the Make Directory
command, mkdir.

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>> If you want to remove a file, you can
remove it from the terminal with rn,

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followed by the name of the file you
want to remove, and typing y for yes

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when the terminal asks you
to confirm the deletion.

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>> Be sure to explore terminal.

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There are tons of keyboard shortcuts
to help you out.

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Also, gedit actually has a small
terminal at the bottom here where you

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can do the same things we did
in our bigger terminal.

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>> For now, let's compile our code
with the following command--

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make hello.

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Now you should see a line with
a bunch of commands.

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Make is essentially a wrapper that just
sends a list of commands to the

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terminal when you type
in that one word.

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In this case, it's running clang, a
compiler with a set of instructions--

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flags--

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on how to compile the program.

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>> Now that we've compiled hello.c, if we
ls, we should see an executable file

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called hello in our directory.

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We run it by typing ./hello, and
there's our program output.

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>> Hello, world.

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My name is Zamyla, and this is CS50.

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