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In this video, we will learn how to check multiple conditions in one statement using a logical OR statement.
Additional Reading
- Operator summary
- Example of an extreme cat lover to use for your logical comparisons.
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Now that we know how to block
on a single specific word.
0:00
Let's expand our reach, and
block more than just one offensive word.
0:03
Now one trait that we have at our
disposal, is that we can check
0:07
multiple conditions by using what is
known as a logical or expression.
0:09
Which means we can do something like this,
if the noun is dork, or
0:14
the noun is jerk, exit the application.
0:19
In fact you could chain these or
statements on forever.
0:22
Let's go introduce a logical OR
0:26
into your application to block the user
from entering either dork or jerk.
0:28
Blocking against the word jerk in
our code is actually pretty easy.
0:34
In fact the only thing I think I need to
show you is what OR syntax looks like.
0:37
So let's go to our IF statement when
we were checking for dork in the past.
0:41
Let's add an OR statement in here, so
we're gonna do a double pipe symbol.
0:45
Pipe is above the enter key.
0:50
That's what OR looks like so
it's gonna say noun
0:53
equals ignore case or
noun equals lowercase on jerk.
0:58
Great.
1:05
Now this line is getting a little bit long
and in fact if we added one more OR on
1:06
here probably go off the screen and then
somebody might not see that it's there.
1:10
So one way that we can do to battle
that is because we're inside of this
1:13
parenthesis here.
1:16
We can add a new line and
take advantage of that space.
1:18
So now looks much better.
1:22
While we were writing that, one thing that
you might have thought was that you could
1:25
do the same thing with two if statements,
right?
1:28
You could write this if statement here
you could say equalsIgnore "dork" or
1:30
you can make another one that
says if noun.equalsIgnore "jerk".
1:35
But what would happen then is that you'd
be writing these same lines inside of
1:39
these, this code block here,
you'd be writing that same code twice.
1:42
And that's never a good idea.
1:45
All right so let's give this a go.
1:47
I'm gonna save it and
then I'm gonna compile and run.
1:48
I'll say 20.
1:55
And we will do big and we're gonna put
in jerk here, great, we caught it.
1:58
So let's walk that really quick.
2:04
So what we've done here is we have this
first line that's gonna come in here.
2:06
It's gonna say noun, and we put in, jerk.
2:09
So noun is gonna be jerk.
2:11
And it says, if noun equals dork,
and that's a false.
2:12
So that's going to say false.
2:15
So, false or true.
2:16
Right, because noun equals jerk and
it does so we're going to say false or
2:20
true and if you imagine that
anytime there's a true in there.
2:23
It's gonna be true.
2:27
Okay, so
let's make sure that the dork still works.
2:28
Awesome it does after using this a bit,
2:37
I think we need to do something
different about that exit.
2:39
It would be good to give the user
a second chance to enter a nicer word.
2:42
Let's see if we can't fix
that in the next lesson.
2:46
And one more thing I wanted
to show if you wanted to do
2:48
another one of these you can always
chain them with another one.
2:51
So right?
So if we wanted to say.
2:53
Another guy here, say nerd.
2:57
All right perfect and
that is how Ors work.
3:02
Great we just learned one way that we
could check multiple conditions in one
3:08
IF statement.
3:12
By not making two identical code
blocks we avoided repeating ourselves.
3:14
A goal of programming is to make sure
that you don't repeat yourself or
3:18
often referred to as DRY.
3:22
As you advanced through your learnings,
you'll hear this phrase often and I'm sure
3:24
it will be hammered into your thinking
as you begin coding bigger applications.
3:28
What were you thinking about logic?
3:32
I'd like to also introduce you
to ORs counterpart which is AND.
3:34
Well OR
returns true if any statement is true and
3:38
will only return true if
all expressions are true.
3:42
Logical and
use the double ampersand simple
3:46
as this logic is such an important
concept and used all over the place.
3:50
Let's go back and
review our dating site analogy.
3:54
So an example of an OR
statement is must love cats or dogs.
3:57
A cat lover would be tested and
she'd say, do you love cats?
4:01
And she'd say gee, yes,
yes, yes, yes, yes.
4:04
No need to ask about dogs as this
person definitely met the requirement.
4:07
Now let's look at another example.
4:11
The request is younger than 40 and
has no children and loves art.
4:13
This elderly gentleman has
prompted how old he is.
4:18
And there is no need to go on asking any
further questions as he doesn't meet
4:21
all the conditions.
4:25
Okay, so
4:26
let's take a really quick exercise
around the statements before we move on.
4:27
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