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Welcome back.

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Let's talk about the topic of formatted strings.

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Up until now we've just written simple strings but we want a program that's dynamic that's static.

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Let's say we have a Amazon page and we're working on Amazon actually.

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And when a user logs into their profile while we want to display their name or what they have in the

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cart in that case we don't want to just hard code and write every single user's name like Andre or another

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user Joe and write every single name in the world.

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No.

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Ideally what we can do is have something dynamic where let's say it's a profile page and we simply use

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the name variable and we display that on the page.

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Now this name variable should equal whatever the user's name is.

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And this is something that we can graph from the database.

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Again something that we'll talk later on in the course.

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But let's assume that in here when we do equals we're going to grab some user information which will

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be the name and this name for now will be John.

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All right let's go Johnny and this Johnny.

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We want to display on the profile page and we can do that with formatted strings we can simply do something

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like print and then say name but we also want to greet that person.

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Right.

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So let's do hi and then plus name and remember to add a space if I click Run I get high.

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Johnny but as we get more and more information let's say we have H and Johnny is fifty five.

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If I wanted to extend the sentence and I want to say you are.

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And then add another plus make sure we add a space in here and then add year old Ron here.

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All right.

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We get a type error must be string not INT.

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Oh boy.

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All right.

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So we have to convert this into a string so remember we can do that like this.

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And then if I click Run Hi Johnny.

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You are a 55 year old or years old.

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All right.

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That was a little cumbersome but we're making our Amazon page dynamic we can grab different information

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from the database and we'll have in a string something according to the user but there's a better way

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of doing this.

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And with formatted strings all we need to do is add an F. at the beginning in this f at the beginning

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is going to tell Python hey this is going to be a format it's shrink and instead of doing all this plus

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and name and all this stuff and doing the SDR to convert the type we can simply do something like this

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Let's remove this and simply do brackets and say name and then again remove all of this

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and say H.

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So I'm going to say hi name you are eight years old and if I click Run here you see that it still works.

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This is a new feature of Python 3 by adding F to the beginning.

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It's saying hey this is going to be a formatted string and I want you to just make these variables available.

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Strings inside of well this string how much cleaner is that now.

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Although this is nice and clean and this is my preferred way of writing strings before Python 3.

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You didn't really have this so in python 2 and mind you this works in Python 3 as well as you can see

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we had something different to accomplish this what we had was this idea of a dot format and Dot format.

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So let's remove the f here is going to do the same thing for us we do a bracket here and then we say

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hey we want Johnny and age of 55 and we can just remove these variable names if I click run here.

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I get an error and you have to be careful here.

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Dot format works on strings.

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You can see over here that we did it outside of the brackets and what it's doing is saying hey run the

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format action on this print but print is not really a string right.

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So you have to make sure that we move the brackets to the outside so that we evaluate this piece of

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code first.

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So the string is going to get formatted and then we're going to print if I run this hi Johnny you are

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55 years old so that works the same way.

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But what if we wanted to use variables because right now we're just doing this by order.

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So whatever comes first gets filled in first in the brackets.

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Well we can do something like name and age.

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Let's see can we do that.

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Let's run.

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There you go.

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That works the same way.

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What if we had a specific order maybe we want this to be h in here to be name.

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Well we can mix those around.

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We can say 1 here and 0 here because in computer science we always start counting from zero.

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So this is zero.

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And this is one if we had something else in here let's say a third variable then this will be so if

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I click Run here all right.

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Everything is upside down.

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Finally I can just create my own variables if I wanted to.

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So let's say Hi let's say new name equals Sally and then age of Sally is going to equal let's say 100

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Sally is very old.

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Now if I do zero let's say I'm one here.

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Quick run.

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So now we'll actually get an error tuple index out of range.

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Now we haven't really learned about tuples and ranges and this is the low confusing but a bit of a trick

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here.

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We want to make sure that we add now because we've given the actual variable a value.

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We need to actually say new name here and here will be h so that if I click Run there you go.

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Hi Sally.

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You are a hundred years old as you can see with DOT format things are a little bit more complicated.

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You'll still see this and all Python to code still uses the dot format and you'll see a lot of Python

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3 code bases that still use dot format because some people prefer it but I would argue that the f at

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the beginning of a formatted string is the way to go because well it just makes things so much easier.

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Right.

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Nice and clean nice and easy.

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So I do recommend that you use the formatted string with the F in front.

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And for short we usually call this an F string.

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All right I'll see in the next one.

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Bye bye.