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There are lots of different ways to run your Python code,

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but when you get into an actual job, you're going to be using

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your command line more than anything else.

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And so in this course, we're actually going to look over two different ways.

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We're going to go over rather two different ways of running

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your Python code.

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The first one is the command line, which I really want you

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to get familiar with just at the very beginning.

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And the second way is using a Jupiter Notebook, which we'll

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cover in a different lesson.

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But for now, what I would like you to do is open up your

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terminal or your command line program.

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For me, it's called Terminal.

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If you're on Windows, that's probably - 'cmd', 'cmder', or

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PowerShell. And if you are on Linux, it's probably like Bash

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or some custom terminal that you've downloaded on your own.

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And let's go ahead and type 'python -V',

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and that's going to show us the current version of Python we're working with.

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We can also type 'which python', and it will show us exactly

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where the Python program is being called upon.

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Now that's actually not super important.

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Mines going to say 'pyenv/shims' because I'm using 'pyenv',

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yours might say something totally different.

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But regardless, it will say something. That's not actually

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writing any Python code.

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That's actually just figuring out where Python is installed

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on our computer and showing us the version. To get into Python,

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our Python shell, where we can actually write Python,

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just type the word 'python', and hit 'Enter'.

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And here we can see that I'm using Python 3.7.2.

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I think this is when I set the 'default'.

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I'm not entirely sure why that is so far behind, to be totally

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honest, but there's a little help in here as well.

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So "Type "help",

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"copyright", "credits", or "license"

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for more information". Let's type 'help'.

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Okay. "Type 'help() for interactive help or help(

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object) for help about object".

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We don't know about objects yet,

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so let's just keep this simple and

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type 'help()', and it gives us a bunch of information in here.

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This is kind of cool.

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"Welcome to Python 3.7's help utility!". "To get a list of available

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modules, keywords, symbols, or topics, type "modules", "keywords",

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"symbols", or "topics". So let's type 'modules'.

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Now, we aren't going to learn what all these are right away.

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This is just sort of exploring the command line a little bit.

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And so that showed me some stuff. That's kind of cool,

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but I want to get out of here.

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So let's type 'quit'. Did nothing,

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or so it seems it did nothing.

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What I actually did was get rid of the 'help' tool that we were inside of.

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So we are technically inside of a program in our command

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line. Now, 'help' is a super useful function when you're just

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learning Python.

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But to be totally honest, it is not super fun.

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I can't run 'clear' because I'm not actually on my command

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line. I'm actually inside of Python.

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So I'm going to clear up some of the stuff.

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And to write your first Python script is incredibly simple.

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So type the word 'print', with a parentheses, an opening parentheses;

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use a quotation mark, and say

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[no audio]

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"Hello World", end it with another quotation mark.

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We've got an opening one right here, and we have, sorry, we

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have an opening one right here, and we have a closing one over here.

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Same thing with parentheses,

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we have one here, and we have one here.

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Go ahead, hit

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'Enter'. It says "Hello World!".

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And just like that, if you have followed that along on your

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computer, you have actually written Python.

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It's literally that easy.

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So right now we are inside of our Python interactive shell.

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We can do all sorts of Python stuff in here, and we're

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going to be using this and Jupyter Notebook throughout

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the rest of the course as well.

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Now to get rid of this, to get outside of this, because currently

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we're stuck in like a Python program,

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just type 'quit' with opening and closing parentheses, and

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you'll get outside of your Python program.

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And to get back in, simply just type 'python'.

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'quit()'. And if you are one of the unlucky people who has to type

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'python3' in order to see the Python 3 program actually

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execute on your computer, you simply just type 'python3',

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and that will go into your Python 3 shell.

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You can actually see for me that changed my version of Python

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as well to Python 3.8.

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And same thing, 'quit()'.

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Now, last thing to note is Python files are usually stored

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in some sort of 'python file.py' file.

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'.py' is the extension here.

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That's the important part.

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And to run your Python file is simply just running 'python',

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and then the file name.

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And so this is getting into command line stuff again, because

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this is the program you want to call.

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And this is the first argument. You're saying, "Hey, run Python.

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But don't just give me the shell,

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actually run this file".

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Now, this file doesn't exist.

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We'll get into that a little bit later. But that is how you

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would run a Python file.

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One last thing to keep in mind, again we'll talk about this

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much more down the road, is Python is case sensitive, and

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it's also indentation sensitive.

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So we don't use things like curly braces like you see in

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JavaScript, or PHP, or in a lot of different languages.

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We don't really use curly braces too much in Python.

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Instead, we use indentation.

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Makes our code nice and easy to read, makes it nice and easy to debug.

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And honestly, a lot of people really love the fact that it

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uses indentation rather than curly braces. I love it.

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I thought it was weird at first, but I actually love it now.

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And it is so much better than writing curly braces everywhere.

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So what I would like you to do is open up your command line

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program, type in 'python', type in 'print(

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"Hello World!")'

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just like I did, hit 'Enter',

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and you'll see "Hello World!",

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then 'quit()'.

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Once you've done that, you've successfully written some Python,

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and it's time to move on to the next lesson.