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Sometimes you may need to interrupt the
normal flow of a loop, to either jump out

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of it completely, or stop the current
iteration and move on to the next one.

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In the next two videos, we're going to look
at the continue and break statements

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that we can use with loops. We need some
examples to show how these statements

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can be useful, so I'm going to start by
introducing lists. We will be looking at

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lists in more detail in the next section
of this course, so this is a very quick

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introduction to what a list is. So list
in Python is an ordered sequence of

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values enclosed in square brackets. For
example, we might have a shopping list.

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So what I'm going to do is create a new
Python file here called shopping.py

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and let's start by defining a list.
So I'm going to type shopping underscore

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list is equal to and square braces, as I
mentioned, or brackets as the case, as you

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may call them, and I'm going to enter
some items that we might buy when we go

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out shopping. I'm going to put, and
because they're strings I'm going to put

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them in double quotes, so milk is the
first one, separating each one, each item,

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by comma pasta comma and obviously, as
you can see, double quotes around all of

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them comma because they're strings,
spam comma bread comma and the last one

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rice, and then that hasn't got a comma
because it's the last one and then we've

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got our square brackets as well. So that
defines our list containing six items.

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Now you saw that those items were strings
but we could use numbers instead. In fact,

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you can store any type of object in a
list in Python, but we'll stick with

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strings at the moment. So make sure you
do use square brackets when creating the

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list, as I've done. So we've bound the
variable shopping_list to our

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list and we can now use that in a for
loop to print out all the items. So let's

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add some code for that: for item in
shopping_list colon.

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Then line 4, print parentheses
double quotes buy space plus item

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and if we run this now,

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and we now get a reminder to
buy each item in the list.

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So that's simple enough. It's a basic for
loop that iterates over the list and

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prints out a message containing each
item. But what if we don't like spam?

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Well we've seen one way to deal with
that. We could check for the current item

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not being spam,d before printing the
reminder. So let's try some code there.

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So we could add it above the print: if item is
not equal to, spam in double quotes colon and

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then we need to indent the print. So
we're only printing if the item isn't

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spam. And looking at the list down the
bottom, it currently does have spam. If we

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run the program, you can see that spam
has now been excluded from the output.

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So that's one way to exclude
spam from the output, but there's

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another way in loops and that's to use
continue. So let's see how that works.

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What I'm going to do is comment out this
loop, just for now, so you've still got

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the code if you're downloading it, and
let's try another approach. Line 7, I'm

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going to type for item in shopping under
score list : if item is equal to, so two

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equal signs spam in double quotes :
continue, otherwise I'm going to go down

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to line 11 there, print parentheses
rather, double quotes buy space in those

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double quotes plus item. Then we've got
our right parenthesis. Now remember to be

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very careful with your indenting here, as
always.

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The call to print is indented to be at
the same level as if, so it's not part of

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the block controlled by if. So when I run
this, looking at the output we had last

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time down the bottom of the screen,
running it now, you can see we've got the

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identical output. So spam is still not
included. Basically, all the items except

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spam have been printed. Alright, so
let's have a closer look now at what's

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happening here. So we're going to set a
breakpoint on line 8 here, that's the if

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checking to see whether the item is spam,
and let's run the program now in the debugger.

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Then we're going to kick straight over
to the console tab, if you're using

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IntelliJ or PyCharm, then obviously I'm
using IntelliJ, as you can see, because we

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can see the values of our variables
printed in the Edit window at the top.

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Alright so we've entered the for loop and
you can see the item is currently milk.

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That doesn't equal spam so therefore
line 9 won't be executed, so we step over,

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and you can see we step straight over to
line 11. So if I step over again now,

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you can see buy milk has been printed out to
the console and we're back now again at

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line 7.
So step over again, and this time you can

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see the item has changed to pasta. Now
that also doesn't equal spam, so I'm

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going to step over twice more to get
back to line 7, and you can see buy pasta

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has appeared in the output pane as well.
The next item will be eggs, so I'm going

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to step over three more times; one, you
can see item's now eggs, and two more times,

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and buy eggs has appeared in the console
window and we're back up to line seven

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again. So next we're going to get to spam,
so I'm going to step over it and we

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should get to line eight. You can see
item is spam. This time the condition will

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be True and line 9 will execute.
Let's step over to check that.

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Alright so we're now ready to execute the continue
statement on line 9. continue causes

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all the remaining code in
the block to be skipped,

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so execution will jump straight back to
the for statement. So let's step over and

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confirm that, and you can see what
happened there. We jumped right back to

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line 7. So that's what continue does.
When it appears in a loop it causes

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everything else in the
loop to be ignored.

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We've avoided doing any processing when
the item is spam, so if we step over again,

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you can see item is now bread. I'll
continue stepping through now, to let the

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program finish, and you can see the
program has now completed. Alright.

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So that's what continue does. You probably
won't use it very often. It's there if

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you need it and you now know what it
does, if you come across it in code that

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you have to work with.
I'll finish this video by comparing our

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two bits of code.

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The code that's currently commented out
on lines 3 through 5, produces exactly the same

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result as the continue code on lines 7
through 11. If you've decided that you

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never have to use continue, then you're
correct. In fact, a lot of languages don't

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have the equivalent of a continue
keyword. Where it can be useful, though, is

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in making code easier to read. So check
out the responses to this stack overflow

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question that I'm about to put on the
screen. Link, as always, is in the

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resources section of the video, and
someone's asking the question there, as

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you can see, some example, for some
example uses of continue, and there's

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some good examples there you can read
through, of using continue. Basically, some

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other opinions from people there, about
continue. Certainly a useful read.

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Alright, so coming up next we're going to
start talking about the break statement.

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See you in the next video.