Welcome back.
And let's talk another term.
Logical operators.
And they're very, very useful when it comes to conditional logic.
Let's have a look.
Logical operators are.
Well, as a matter of fact, you've actually seen them before and is a logical operator.
Or is a logical operator, it allows us to perform logic between two things.
What else is a logical operator?
Well, let me list it out for you.
We have greater than.
Less than.
Equal to.
Let's actually use them in an example is for greater than five.
Well, if I print this.
What do you think will happen?
Shouldn't be a surprise.
That's false.
Four is not greater than five.
This is a logical operator that you may have seen in math class.
If I do, the opposite is for less than five.
That makes sense.
That's true.
What about is four equal to five?
If I run this, I get false.
Now, why did I use two equals here?
Why not just do this?
Well, if I run here.
I get an error syntax.
Error keyword can be an expression.
It's because, remember, equal is what we use to assign to a variable.
Right.
And if you remember, I told you that a variable in Python can start with a with a number.
It has to be a letter or underscore.
So when I do this, it's going to air because the interpreter is going to say, Hey, I'm trying to
assign variable for the value of five, and well, that's not really allowed.
So we use double equals to tell the interpreter, Hey, I'm not assigning a variable here.
I want to compare things and we can compare different things.
I can do.
Hello equals two.
Hello.
Equal to true.
What if I do A is greater than B?
I get false.
Now, why is that?
This.
I want you to Google on your own and figure out why is a greater than be.
What if I do?
A is that greater than capital?
A.
That's true.
Hmm.
This is this is interesting and this is actually quite an interesting reason.
So I know I know it's easy for me to just give you an answer, but I want you to practice Googling this.
And the reason I'm not giving you an answer is it's also because it's not very important, because most
of the time you want to make code that is easy to understand and understandable.
You're most likely using greater than less than with numbers.
So if you see something like this in code, well, you wouldn't know what's going on.
What is this person trying to compare?
Why are they doing?
Is lowercase a greater than capital?
A It's not something that you see very often, but the reason you get this expression is quite interesting.
So I do recommend you Google Google into it.
Like I said, I'm a strong believer in not holding your hand the entire way.
I know so far the videos up until now have been quite easy, especially if you are an experienced programmer.
But as we progress, you'll see that after this course you need to figure things out on your own.
And my job is not to just hand-hold you the entire way, it's to develop the skills in you to become
an employable programmer.
So I hope you bear with me as I just give you this little challenge.
All right.
We want a bit on a tangent, so let's bring it back.
Can I do things like this?
Is one greater than two?
Or you know what?
Let's do less than two and less than three and less than four.
Will this work?
Well, of course it will.
It's just an expression, right, that we're evaluating.
And all of this is true.
But as soon as I change.
And something is false.
It's going to short circuit which we learned about previously and return false.
All right.
So we know the greater than equal to less than sign.
We also have greater than or equal to.
So that if I do.
Zero here and I click Run.
I get true because it's saying, hey, is this greater than or equal to zero?
I can also do less than or equal to zero.
And here I get false because zero or one is not greater or equal to zero.
But if I do zero here, I'll get true.
Here's another one.
What if I do this?
Exclamation mark equal.
This means in Python, not equal to.
If I run this.
I get false.
And this is a little tricky.
What it's saying is, hey, is this not equal to this?
So it's the opposite of doing equals.
If these two things don't equal, it's going to say true.
So if I do one.
Here, I'll get true because these two things do not equal.
So we've learned greater to or less than greater to equals equals or greater or greater or equal to.
We've learned about less than or equal to.
We've learned about.
Not equal to.
But we've also learned about.
End and or.
And finally, there's one more I want to teach you.
And it's the not.
Keyword.
I know.
It's.
It's a little.
It's a little much, but it's not as hard as you think.
Not is.
Well, the opposite.
So if I do hear.
Not.
True.
What do I get?
I get false and you see that not as also a function.
So it's a keyword, but also a function that we can use.
If I do not false.
Again.
I just get the opposite.
What if I do this?
What if I do not want?
Equals to one?
Well.
Will I get here?
I get false because this expression evaluates to true and then not just does the opposite.
So let's take a break here and work on a little bit of an exercise to make sure that we understand this.