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Welcome back.

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So far we've learned a few built in functions that Python has few built in actions right.

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Actions that we can take on data and we learned about SDR.

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We learned about it.

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We learned about float and the type conversion that we can do.

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We also learned about type.

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We also learned about print and these built in functions in python.

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Well there's a few of them and all linked to this resource but there's not two too many.

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As a matter of fact we've also seen ones like a B.S. or round in our numbers video so numbers had some

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functions that we can use some built in functions well strings also has a very useful one called Lent

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which stands for Lent.

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So as you guessed it if I type in something like this and I print this out and I click Run I get nine

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because it's calculating the length of the string.

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In our case one two three four five six seven eight nine.

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The length of the string is nine.

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Now you have to be careful here because the length itself doesn't start at zero as we've seen with indexes.

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Instead it counts like humans do from 1.

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So a neat thing to do here is I can do something like this Let's say that we have a variable greet that

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equals Lou.

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Well I can grab the great variable which has a string and use String slicing to grab.

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Well the first and then goal all the way until the end.

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Now the default already does this.

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If I leave it like this it's going to grab hello and make sure I add a bracket here.

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Let's click Run I get Hello.

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Now if I do 0 to length of

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what does that mean.

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Well if I click Run I still get Hello.

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Because the length of Grete is nine

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like so now.

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This length function is quite useful and we're gonna use it a lot in this course.

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But I want to introduce to you the concept of built in functions as well as what we call built in methods.

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What does that mean a built in function had the syntax of the word that was highlighted in blue and

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then we used curly brackets to perform some action on a data type however Python also has this idea

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of methods and methods are similar to functions but they they are owned by something.

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So for example in Python we have string methods.

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So these are methods or actions that only strings can perform and don't worry.

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This is something that we'll talk more about when we talk about classes and functions.

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But for now Python for example has a string methods.

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So these are methods that we can use specifically for strings and methods have a special syntax where

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instead of just the word with the curly brackets it usually has a dot in front of it.

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So dot and then some sort of word and we've actually seen one format right Dot format.

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Curly brackets or brackets is a method.

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And if I go to Python string methods and I scroll down or scroll up we see that format format specific

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values in a string is a method now why do we care.

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Well with this python gives us automatic tools that we can use on strings.

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So let's explore some of these string methods let's create a quote here and the quote is going to be

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to be or not to be now in here with this quote We can use some methods on this string.

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Now I'm not going to go through everything because while 60 percent of these you're most likely never

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going to use in your career I'm going to go over the important ones that you'll see over and over again

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but I'll also linked to this so that you can see this for yourself as a reference.

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Remember as a programmer your job is not to memorize this and read a language like you read a dictionary

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instead is to know that this resource exists and it's for you to explore and learn as a specific problem

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occurs.

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But let's get back to the task at hand.

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One thing that we can do is to use the upper method.

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We use a dot and then type in upper and then the curly brackets.

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And luckily for us our editor shows us that this actually exists because of the dropdown.

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So what happens now if I print this and I click Run look at that.

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Everything gets capitalized to be or not to be.

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There is also another one we can use called capitalized.

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What's the difference between the two well if I run.

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You see that it capitalizes the beginning of the sentence and by the way your editor or in our case

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our rebel if you hover over this they'll actually tell you what it does it returns a capitalized version

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of s so whatever is to the left of the dot and a good editor will actually show you all the things available

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to you.

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So as soon as you press a dot look at that I see all these purple boxes which are methods that are available

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to me for a string and you see there's a lot of them.

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Now don't worry about these double underscores these Dunder methods because this is something that we'll

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talk about when we talk about classes.

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But he can see that you have different things that you can use.

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For example you have lower instead of upper in lower cases everything What if I want to use find for

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example and find simply says hey does B exist in the code to be or not to be in fact click Run well

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it tells me that yes code dot find has a B and it starts at index of three so if I go to 0 1 2 and then

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look at that 3.

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So we have find which finds us the first occurrence of a piece of text.

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You also have things like replace where I can replace whatever I give it as the first thing and then

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separated to the second thing so you can see over here it tells me old and then comma new and I can

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replace this with me if I click Run I get to me or not to me.

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So this replaces all the occurrences of B.

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Now the final thing I want to point out to you is that if I print here quote What do you think is going

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to happen.

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I've printed here and I replaced.

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To me to be or not to be with.

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To me or not to me.

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Quite a selfish quote but if I print this again on the fifth line what do you think will happen.

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Let's find out

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is this what you expected.

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Think about why this might happen based on what we've learned here's the thing.

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Remember strings are immutable.

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That is they cannot be change.

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We can overwrite them if we want but we don't change them we either create them or destroy them.

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In our case when we do quote da replace to me or not to me it's creating a new string.

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Now we're not assigning the string to anything.

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So eventually after we printed we remove it from memory.

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But if I do something like this where I have quote two equals quote I replace and I print quote to well

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in our case we're creating a whole new string.

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We're creating a string but we never modify the original string because it's immutable.

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So that quote always stays the way it is until we destroy it until we remove it.

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Our program ends.

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This is going to exist.

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Hope you're having fun.

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Hang in there more to learn in the next video.