- [Instructor] One way to execute or run your Python code
is by using the command line.
I'll be referring to it as the terminal
or command line throughout this course.
You can access it on your Windows machine
by going to the Start menu
and then navigating to the Python folder.
When you get to the dropdown,
choose Python 64 bit.
This is going to open up the Python shell.
The Python shell will display the prompt,
which lets us know that the interpreter is ready
for our Python instructions.
Unlike the Mac, you don't need to type anything else
to start sending Python commands.
We'll start out by trying
to get the sum of two plus two.
Let's see what happens when we type
what is two plus two?
And hit Enter.
Well, we get a syntax error from the Python interpreter.
We call that syntax refers to the rules
of a programming language.
Syntax errors happen when you write code
that breaks the expected rules.
In this case, we wrote our code in plain English
but the interpreter doesn't understand English, only Python.
Now, let's try that again.
But this time, we'll type two space plus two
and then hit Enter.
And look, we get back the number four.
That's because the expression two plus two
is valid in the Python programming language.
But what if we were to just type two plus
and then hit Enter?
Well, we get another syntax error
because our expression was not complete.
For example, in English,
I could say you're doing a great job with the course so far.
That's a grammatically correct sentence
but if I were to say you're doing a great job with,
that would be an incomplete sentence.
I didn't finish it up.
Programming languages work much the same way.
They need you to follow the syntax or rules
in order to understand your commands.
For now, let's exit the Python prompt.
We can do this by typing exit,
open parentheses, close parentheses
and then hitting Enter.
Remember our 01_03.py file?
Let's see if we can run the code contained in it.
First, we'll need to open up the command prompt.
To do that, we'll come down to search
and we'll type Command
and we'll choose Prompt.
Next, we need to make sure we're in the same directory
as our file.
My file is located on my desktop
inside of the exercise files folder.
Yours might be in your downloads
or another location.
The first thing we're going to do is to type cd
or the change directory command
and then we need to find the path of our file.
I'm going to open up the File Explorer
and then I'll navigate to where our file is located.
First, I said it's on the Desktop.
I'll choose the Programming Foundations folder.
Then Exercise Files,
and I want the file that's inside of chapter 01.
So I'm going to drag this folder over
to my command prompt.
Now, when we close down the File Explorer,
notice that the entire file path
has been copied for us.
It's pretty sweet.
Next, we're going to type enter.
We're now inside of the chapter 01 folder.
I'll then type the dir command,
which stands for directory
to get a list of all the files
that are contained in this directory
and I see my 01_03.py file.
In order to execute it,
I'm going to type python 01_03.py
and then hit Enter and we get our Hello world!
Throughout this course, I'll be using a Mac computer,
so I'll often refer to Python 3 instead
but for Windows users,
typing strictly Python will work just fine.
Although most of the programs
that you write in your IDE,
you can run directly from there,
you may have occasions
where you want to run some Python code from the command line
and now you know how.