Name: PythonでIf Else文を使う方法 (Pythonチュートリアル #2) (How to Use If Else Statements in Python (Python Tutorial #2))
Uploaded: 2021-01-14T10:21:03.000Z
Duration: 19 min 45 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Welcome to video number two off my python tutorial for absolute beginners in this video.

First of all, I'm gonna ask her a question I received on my last video.

And then I'm gonna give you some additional commands that you can use in Jupiter notebook, for example, for adding and deleting cells.

And remember that you don't necessarily have to use different notebook to follow this course you can use, for example, part charm, which is a popular I d for python.

After that, I'm gonna cover if l statements how to use them and what they are.

And by the end of this video, you'll be able to create a simple B m I calculator, which can tell if a person is overweight or not, given the person's height and weight, I'm gonna put on the outline off this video below, so you don't have to watch the whole thing if you don't want to.

And you can go to see sojo dot io slash python to to download the simple files I create in this video.

First of all, let me answer a question I received on my last video.

The money as REM Sorry for the pronunciation says currently I'm learning Web development.

Should I keep going or start another language like Python?

So I wanted to answer this particular question because I thought some other people might have the same question.

Maybe you started learning c++ or job already on your wondering.

Should I keep going with it, or should I take this course for Python instead?

I would say Keep going with whatever you're doing, as long as you enjoy and then if you want, you can take this course at the same time because some of the concepts I'll teach are gonna be the same regardless of which language you're using.

So, for example, the method for swapping two variables I talked about in the last video You can use that in c++ or Java or in any other language you're lining.

Okay, with that out of the way, let's now talk about juvenile notebook.

First of all, launch did a notebook through Anaconda Navigator or with any other I thought you'd like to use and then navigate to desktop.

I'm gonna call this Python tutorial, too.

Navigate to that folder within Messed up and click new at the top right corner Click Pylon three.

And let's call this file if else statements, click rename and then I'm just gonna maximize my browser window.

So the only command we learned in the last video was this one right here for running or executing a cell.

Once I click it, it executes or runs all the commands within the given.

So if we have hello, one here and then hello to here.

And the print function will execute both of these lines.

And you might have noticed that after running this, sell it automatically as a new cell below it.

This cell For that, you can use this bun that looks like scissors and for adding sales.

You can use this bun right next to it that looks like a plus button, and you can add as many cells as you want on.

One interesting thing here is that you can execute these cells in any order you like.

So let's say you have print a in this cell on a equals one in this.

So you might say, Well, if we try to execute this so it will give us an error, let me actually try it again because A is not defined yet.

Name A is not defined, but before executing the cell print A.

If we execute this cell right below it to define a to be one, it would give us an error anymore.

Delete a bunch of cells here with this scissor spun.

And let's add one cell below the first cell on Let's say we have b e close to here on Let's run it with the wrong button right here.

And of course, this way be is defined to be too.

Now what happens if we delete the cell with this bone right here on?

If we try to print, be right here with print Prentice's B.

What happens is actually, we can still print it because even though the cell containing this statement because two is dilated, the state off, this Jupiter notebook is actually still preserved.

So when I say the state off this Jupiter notebook, what I mean, is pretty much all the variables that are stored in this stupid a notebook.

And the state of this Jupiter notebook is not stored on this browser window.

Because, like I said in the last video, this browser window is just a user interface for the Jupiter notebook.

This Jupiter notebook is stored in something called the Colonel off this jibber notebook that's basically represented by this command line interface.

This might look slightly different if you're using Windows on the Colonel is what Excuse your code once you click the rum bun and also stores all the variables that you've defined.

So to clear out the state of the stupid A notebook or to clear out all the variables you have to find, you need to click colonel at the top and then click Restart.

It'll restart and clear open because it restarts.

The colonel on clears out everything that's been printed.

Now on, if we try to print be now, it'll give us an error because name A is not defined yet.

Also, remember that there's one colonel for each notebook file.

So if we had another notebook file on if we restart the colonel for this notebook file, that won't affect the other notebook at all, because that no book will have a separate colonel.

Okay, So just to recap, we've learned how to use four commands into better notebook.

The first is running a cell, and then the leading sells adding cells as well US restarting the Colonel and clearing the output.

Okay, let's not delete all the sales we have here.

Andi, we start to colonel and clear the output.

And let's dive into our main topic today.

Let me give you a quick example Here A is equal to one on B is equal to two.

That's something like a is less than be by printing this string on Lee.

If Ace actually less than beat, we can do this with, if a less than be Colin.

So that's if space a space less than space be column enter into a new line on print.

You need to invent this new line by four spaces, so that's 1234 You could actually use a different number of spaces, for example, three spaces or five spaces.

But using four spaces is a convention in Python.

So let's stick with four spaces in this video.

So these two lines, if a lesson be prints A's lesson be this whole thing is called an if close.

And after this, if clothes, you could have more code.

And so this if condition on Lee applies to this line in this example on Python knows that because of the Collin sign here, as well as the four spaces that we have before this print mine.

So let's try running to sell because A is currently us, then be we should be able to print a lesson.

Be on we do on Let's see what happens if a three in that case, A is not less than be so.

This cell should Onley print this line right here.

That's indeed the case, and it's actually possible to have multiple lines within the if Klaus.

So instead of just having print A is less than be we're gonna write.

Print double quotes is definitely less than be on in this statement.

Python knows that these two lines are part of the IV clause because both of these lines have four spaces in front of them.

By changing a 21 again on Since Ace listen be, we should be able to print these two lines again.

So we see that ACE Lesson B and es Stephanie less than be so in a different language.

You might see an if close with princesses on with curly brackets, but in python were using a column as well as four spaces in front of each line.

You need to be really careful about the number of spaces in front of each line, because if we had, for example, four spaces in front of the first line on five spaces in front of the second line, it'll give us an error.

So the air says indentation error, unexpected Indians.

Let's fix that by deleting one space here and now we have forced business in front of each line, so it's gonna work again.

Okay, let's take a look at a few more examples here.