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Welcome back.

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In this video, I want to talk about the idea of Truthy and falsey.

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What do they mean, and you'll hear this a lot in Python programming, you see up until now you've used

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booleans here as Valdés.

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So it was really easy, if true and true, then run this code.

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But Python can do other things as well.

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For example, if this was five and this was let's say hello, what do you think will happen here in

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our program?

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Well, if I click, run.

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You are old enough to drive and you have a license.

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Is that what you expected?

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And this is because what Python does underneath the hood is actually convert these to booleans for you,

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so it's almost as if it is doing this remember type conversion where converting the type.

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To Bolian, as soon as we get to this if statement, because Python is saying, hey, I want true or

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false, I don't care what is all this, I don't care what is license's, just give me true or false.

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So I know whether to do this or to go to the else block.

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Now, if I was to just print let's do this here, let's do print Bolian Hello.

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And then finally print Bolian five.

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Let's see what we get.

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We get true, true, and this is what we call a truthy value in Python, that is it's a Truthy value

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because if we run the Bolian type conversion on it, it evaluates into true.

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What's a falsey value?

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Well, if I do zero and if I do, let's say, an empty string and I click run.

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Those are falsie, that is it's not actually false, but it is false because if we run bullion on it

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to Python, it's going to say, oh, this is false and zero, that's false.

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And that kind of makes sense, right?

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And if you actually go to stack overflow, if you've never seen Stack overflow before, if you ever

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have programming questions and you're Googling them, usually the top five answers will contain either

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one or two stack overflow answers.

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And basically what happens is people ask questions like what is truth and falsity in Python?

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And you get answers.

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So you can see over here that it has four answers and you usually look for the checkmark, which means

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that this is a verified answer and means that, hey, this question owner has accepted it as the best

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answer.

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So the person who asked this question just said, yeah, this is the right answer.

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This is the best one.

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But you also have other people voting.

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So you can see that this answer received 46 marks.

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And although it was marked as the correct answer by the user, maybe somebody else came along later

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on and gave an even better answer.

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So now we have one hundred and twenty three upvotes and you see that this answer is a lot better.

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All values are considered Truthy except for the following.

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So you can actually see here that in Python, these values are considered falsey, you can see zero

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here.

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You can see an empty string here and then there's a few other ones empty set.

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You have an empty dictionary, empty list, empty tuple.

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You have decimals.

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You have things like fractions.

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You have zero point zero falsies.

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That and also none is falsey.

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So that if I type in none here.

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That's false to.

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Now, you don't need to memorize this because most of the time it it makes sense, right?

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But it helps us do conditional logic very nicely.

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For example, let's remove this and let's say that we have a user and this user has to have a password

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and a username.

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If let's say the username is Johnny and the password is one, two, three.

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Well, instead of me saying, hey, if this user has a password and username and we're not checking

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if the username exists or password exists, we just want to make sure, hey, did this person fill out

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the form and did they try to submit a username and password?

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I can just simply say password and username.

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And I don't have to worry about converting this to a bullion or anything like that, because if password

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and username exist, then try to lock them in and you see that it reads a lot nicer because each one

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of these get evaluated into a truthy and falsey value.

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It's a nice little feature to keep Python well, nice and simple and reading like English.

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I'll see in the next video by.