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Our first requirement for the widget store
program is to print a welcome message for

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the user.

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Before we can start coding, we're going to
need a file to hold our Ruby source code.

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Ruby source code is stored
in plain text files but

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instead of .txt,
the file usually ends in a .rb extension.

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So to create a Ruby source code file,

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we're gonna go to the File menu,
we'll choose New File.

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And we'll type a name for
our file of widgets.rb, and

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that will create a widget.rb plain
text file and open it in our editor.

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Now we need to print a welcome message.

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We can do that using the puts
method which stands for put string.

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So let's try that now.

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We'll make a call to puts, and
we'll pass it a string here within

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the quote marks, and
we'll just say hello world for now.

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Go to your File menu, and choose Save
when you're done to save your changes.

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To run a Ruby program, we need to run the
Ruby command in the terminal or a console.

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So click down here in the Console area,
and

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then type ruby, a space, and
the name of the file you want to run.

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So, that's widgets.rb.

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As long as you're in the same folder, or

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directory as that file, then all
you need to type is the file name.

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And you can see that down here,
the program runs and

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it prints our message, hello world.

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If you're in a different folder or
directory than the file you want to run,

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then you're going to need to change into
that directory before running the file.

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So let's try creating a new folder here,
we'll call it my_folder.

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And then we'll create
a new file within it.

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And we'll call it other.rb.

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And we'll just do another simple program
in here that prints out other file.

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Go to the File menu and choose Save.

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And by the way a shortcut, if you want is
you can hold down the Cmd key on MacOS,

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or the Ctrl key on Windows and
press S to save the file.

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We'll be doing that a lot for
the rest of the course.

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So now we have this file named other.rb
saved in a folder named my_folder.

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If I try going down here clicking in
the Console and running ruby other.rb,

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it won't work, because there's no file
named other.rb in the current directory.

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Instead, we need to change directories
using the cd or change directory command.

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And we need to type in
the name of the directory or

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folder that we want to change into.

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So we'll change into
the folder named my folder.

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And now that we're in this other
directory, we can go ahead and

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run the other.rb program and
Ruby will find it successfully.

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And there you see it prints our message,
other file.

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But we don't need to do
any of that right now,

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we're okay working in just the one folder.

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So I'm going to change back to the parent
directory using this special notation

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here, .., which means the parent
of the current directory that

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is the directory that holds
the current directory.

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And I'll hit Enter, so that I'm back
in the workspace folder where I began.

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And now I'm going to delete my_folder.

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And that I'll delete
the other.rb file along with it.

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Now let's take a closer look at
the code within our widgets.rb file.

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Puts is a method,

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a group of code statements that
together perform a particular task.

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Puts stands for put string, and
that's the task it carries out.

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It puts a string of text
characters on the terminal output.

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Typing the method name here calls
that method or causes it to run.

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The text here inside quotes is a string.

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We'll be talking more about string soon.

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Because we are putting the string
here following the method call,

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it's passed as an argument to the method.

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Methods take the arguments that
are provided when they're called and

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work with them in some way.

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Puts just prints whatever arguments
it receives out to the terminal.

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Let's add a few different
method calls here so

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you can see what I'm talking about.

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First, we'll make another call to puts,
and this time,

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we're going to type parenthesis
following the method name.

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We'll pass at several arguments.

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If you're passing multiple arguments to
a method, you separate them with commas.

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So we'll pass a couple of
numbers here as arguments, and

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then we'll pass a couple of strings too.

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And then we type a closing
parenthesis to end the method call.

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Now let's make another call to
a different method, one called sleep.

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What sleep does is it causes
the program to pause execution for

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the number of seconds you specify.

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So you pass an argument with
number of seconds that you

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want the program to sleep for.

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Now let's add another method call.

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This one to the print method.

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Print works a lot like puts except
that while puts skips to a new line

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after each new argument that it receives,
print just stays on the same line.

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So we'll pass a couple more
string arguments to print.

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Let's say, c and d.

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And then let's make one more call to
sleep, and we'll just have it sleep for

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one second this time.

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We'll hit Cmd+S to save this,
Ctrl+S if you're on a Windows machine.

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And now let's click down here on
the Console, and run the program again.

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We'll hit the up arrow to bring
the previous command back and

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run ruby widgets.rb.

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And you see that as before,

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it makes a call to puts with the string
hello world and it prints that out.

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And then comes our call to puts
with the numbers 1 and 2, and

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the low strings a and b.

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And you can see that each of those
prints on a separate line down here.

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If we rerun the program again, you'll
notice that after it prints one 1, 2 a,

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b, it pauses for a couple seconds before
printing c and d here on the same line.

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That pause was due to the call
to sleep with an argument of 2,

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it slept for 2 seconds.

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Then the call to print printed
the string c and d on the same line.

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And finally, the program slept for
one more second before ending.

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Parentheses are optional
on Ruby method calls.

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So, you'll notice that we made a call
to puts up here without any parentheses

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surrounding it.

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We just put a space between
the method name and its one argument.

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We can actually remove parentheses from
all of these method it calls down here,

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and they'll still run in the same way.

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So I'm going to replace the opening
parenthesis each with a space, and

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I will just delete the closing
parenthesis on each line.

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Hit Cmd+S to save that,
Ctrl+S if you are on Windows.

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And let's rerun the program again and

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you will see that it runs
in just the same way.