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So now that we can perform calculations
and just play the results,

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it's time to move on and see how we
can get Python to make decisions and

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also how to perform tasks repeatedly.

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Unlike most programming languages
Python works in blocks of code,

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and actually one of the design
principals of Python

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was that it should be uncluttered and
easy to read.

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Because of this Python's doesn't
use delimiters and blocks of code.

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And so what I'm going to do is
show you what I mean by that, and

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show you the Python solution.

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So, I've opened up a new project, and I'm
going to create a new path and file, and

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I'm going to call it Tabs, for
reasons that will become apparent shortly.

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So firstly, let's just type in an example
in Python on how indentation works.

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You saw this in the previous video,
we create a for loop.

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So for i in range(1, 12 colon.

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And notice when I press enter here,
it's automatically indented by Python.

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So python has moved forward four letters,
or four spaces I should say,

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so that when we start typing the next
part, it's actually indented.

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So this is the concept of indenting.

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And I'm just gonna finish typing this,
and I won't go through the code,

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because we explained that and
went through that in the previous video

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Okay, so and

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if we actually run that we have the
answers that we saw in the previous video.

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Now a point I wanna make though is
about the use of indentation and

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using braces in other
programming languages.

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For example with Java, you can type
something and you'd put if something.

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And to do the same thing with indentation,
you actually put a brace like so,

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and then you'd actually add another brace.

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Now obviously we're getting
an error on the screen now,

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because IntelliJ is saying,
well this is the valid path and code.

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So the point I wanna make is that, you
have to actually denote the code block,

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the code that you want executed in
the middle, by using something.

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Something actually like a brace.

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Well, the deleting this out now in
order to get rid of that error.

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Python doesn't do that.

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So what Python does, it's quite happy when
you actually start typing a statement,

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it's gonna indent that for
you automatically.

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It doesn't use delimiters around
the blocks of code, in other words.

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Now if you actually delete the spaces,
you'll actually get an error.

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So if I should delete those now,
we'll actually get an error on the screen.

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Indent expected.

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And that's because python is actually
saying, it needs at least one space

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to know whether this is part of
the previous line's code in other words.

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So in other words,
to indent it needs at least one space.

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So we could go back up there and indent
that one space and it will be quite happy.

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But generally speaking it will do it for
you.

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So again, on the previous line you
still want to start a topping.

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When I pressed enter there, it
automatically indented it four spaces, and

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if I press delete now I can get that
other code back up there on the screen.

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Now both IntelliJ and
Idol make it easy for you by doing that in

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default indention when appropriate,
and then also continue the indention.

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So if we come back to the end of the line
here, pressed enter, notice that it knows,

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because of you're already in an indented
line, it's assuming that you don't need to

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be indented again, and we can actually
start topping from that point.

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So in other words it's handling a lot
of that for you automatically, and

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also pressing backspace,

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moves the indent when you're finished
entering the code for a block.

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In other words, you can go there.

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So if you're on the next line there,
and let's just say you decided,

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well, you're gonna need
a little more code.

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You wanna go back and
print another statement.

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If I press backspace now, I'll go back
automatically four spaces as you saw there

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to the start line,
I can actually start typing again.

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Now you might be asking, now what
is this block you're talking about?

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Well, Python actually
referred to that as being

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a piece of Python program text
that is executed as a unit.

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So in the example above, you can actually
say that print itself was a call to

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the printer method to be more precise,
is a block.

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Now we could have included some extra
lines at the same level of indentation,

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and they'd become part of the same block.

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So in other words, you could actually
start typing, print, calculation complete.

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Try again, for example.

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All of these are actually part,
in this case, of the same block.

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The reason for that is they're at
the same level of indentation.

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Now when we get to the point in this
course where we're defining our own

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functions or methods,
the body of the function is a block, and

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that may in turn contain other blocks.

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Now we actually need some more complex
code examples to demonstrate this fully,

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so what I'm going to do now is finish by
showing you some of the preferences in

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IntelliJ to do with tabs, and then in the
next lecture we'll start getting into some

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more complex code examples.

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So if you actually want to change
the level of tabs or spaces

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the way to do it is to go into Preferences
IntelliJ so I'm going to select that.

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Preferences and we can go into Editor.

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And because we've actually installed
the Python plug-in you should

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actually see that.

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So, let me go into General and
scroll down into Code Style.

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We can actually see Python,
so I'm gonna select python.

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Once I've actually done that, so

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again that's Editor, Code Style,
Python is how to get to it.

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You'll notice here that
we've actually got tab size.

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The python folder is showing
you that the tab size is 4.

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And what that means is if
you press the tab key, and

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that's to get this little indentation,
if you do that yourself,

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every time you do that's gonna add
four spaces for you automatically.

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Now if you click on
this Use tab character,

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what will happen if we do that,
notice how this has changed now and

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it's flashing to show you that now
this is actually a tab character.

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So what that saying is instead of actually
adding four spaces for you, it's actually

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gonna add the tab character itself for
you if that's what you wanna do.

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So you can play around with this,
you can change the level of indentation,

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you can get yourself a little
bit of difficulty doing that.

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If you do find that things aren't working.

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Come here back in editor,
code style python, click on reset, or

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just make sure that your tab size and
indent is both set to 4.

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And optionally you can leave that on, but

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I'll probably suggest that
you actually leave it off.

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And what that means is that IntelliJ will
automatically be adding spaces, as and

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when you actually need them.

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So, that's what you need to do
if you do get in any difficulty.

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And just to confirm how that works again.

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Because we added four,

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every time I press Tab,
you could see I'm going four characters.

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And that's because we've specified four
in the preferences that the number of

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characters that were gonna move forward.

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And just one final note.

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You don't wanna get into the situation
where you're mixing spaces and

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tabs when you're indenting blocks.

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And the reason for
it is it can get in the difficulty and

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it can get a little bit confusing.

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And IntelliJ does a pretty
good job at that.

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So if you do do that, chances are, it's
gonna fix that and correct that for you.

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But if you're bringing in source code or
editing in another environment and

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then bring it into IntelliJ you might
run into a bit of difficulties, and

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you may have to re-fix things up.

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Also the other thing to keep in mind is,
you come up here to Code.

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Try doing reformat code.

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That can actually help you
if you actually select that.

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That will often actually fix errors.

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So if you've got some weird
sort of formatting and

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things not working, go into other
option and click reformat code and

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that can get you out of
difficulties as well.

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So that's it for this video,
short, sharp, and shining.

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In the next one, as I mentioned,

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we're gonna move on to some more
complex examples of how this all works.

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And specifically we're gonna start
looking at the if statements.

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So I'll see you in that next video.