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Hey, welcome to the Days experiment.

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Today, I'll run a few cold experiments so that you better understand the list indexing and type conversion.

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Now, the code that I'll be trying out are single lines of code.

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So for that reason, I'll be using the Python console.

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It's best to use the python console when you are just executing one liners.

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So you saw that if the user entered some inputs.

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And we store that input in a variable.

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For example, if the user enters five and then you see a now is a string, you see the codes here.

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So a plus ten would not make sense.

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Therefore, you want to convert A to an integer using the INT function and perhaps store the output

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in a new variable or maybe in the same variable.

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It's up to you all store it in a new variable.

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B So now.

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B plus ten makes sense.

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So B is an integer.

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You see, it's without quotes.

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And this has quotes around.

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Now you might ask, why are types important?

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Why can't we just have ten?

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And it doesn't matter if it's a string or a number.

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Why do values have to have a type?

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Well, I'll answer you that with an example.

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So again, A is a string, B is a number.

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Now, if you do B times ten, guess what you will get.

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Yeah, it's 50.

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So five times ten you get 50.

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Now let's try.

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Times ten.

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This is what you get.

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So in Python, it is not possible to add a number to a string, but it is possible to multiply a number

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with a string and the output you get is that string multiplied ten times in this case.

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So five, five, five, five, five, five, five at ten times, and you get a new string.

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And of course, you can have everything like high times ten.

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And you get high, high, high, ten times.

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So back to the question we asked, Why is it important to have types?

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Well, the interpreter wants to know the type because it understands better what you intend to do.

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So if you intend to have that string multiplied ten times, then you want to have that as a string type.

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And then the interpreter knows that it is a string type.

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So I don't have to do a math multiplication, I do a string multiplication if it's a string type.

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And if you as a programmer mean to to do a math operation, then you want to make sure that this.

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Value is an integer.

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So having types for values is important to communicate with the interpreter, so things have to be as

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explicit as possible.

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Right.

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The next experiment.

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If you do it high, you will get an error.

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So that's obvious.

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You can also use floats.

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Floats high, you will get an error again.

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So it doesn't make sense to convert that string into an INT and it doesn't make sense to convert that

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into a float.

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So floats are decimal points and numbers.

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If you convert.

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String ten to a float, you'll get 10.0.

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So that is different from converting string ten into INT you get ten.

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So again, we have a different type here.

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The distinction between floats and integers is not as important as the distinction between strings and

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integers, but still you don't use floats whenever you are working with continuous data.

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So if you have a variable which is the temperature, then you want to work with a float.

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If you are working with whole numbers such as the number of persons in a company, you want to work

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with integers.

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Now Python has this implicit declaration of types so you don't have to use the float class when you

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create a variable.

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So if you just say x is equal to ten points one and you check the type of x, you'll see that x is.

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A float.

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But if you do, y is equal to ten, you'll see that Y is.

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An integer.

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So if it doesn't have that dot.

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It's an integer.

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If it does have that, it's a float.

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And of course, if you use quotes around it, it doesn't matter if it does have the delta or not.

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Type of set is going to be a string.

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If for some reason you want to convert a number into a string, you can use a STR.

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You not only convert integers to strings but also floats to strings.

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You could ask when would you need to convert a number into a string?

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Well, you'll see that when we create apps, then this SDR function can sometimes become useful.

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For example, if you want to write some texts in a text file via Python, there is a method for that

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which you will learn later on in a few days from now.

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And in that case, you cannot write a number to other types to a text file.

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So if you have a number, you'll have to convert it to a string and then write the output in that text

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file and then the number would show in that dot txt text file or other file formats that Python is able

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to create.

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Let's run a few experiments on the list indexing now.

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So let's create a list.

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My list is equal to.

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A, B, and C.

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The first thing I want to make sure you understand well is that each of these items is treated as an

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object.

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So you can stroke the object, you can store it in a variable, for example, as that is equal to my

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list.

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One and Z will be string B, So the type of Z is be sorry, the type of Z is A string that B was another

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variable which we declared somewhere in here.

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So that is a string.

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And with that we extracted the item with index one.

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So a has an index of zero, B has an index of one.

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That's why we get the string B and of course you can do other operations.

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You can say that is equal to B, you get true.

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Similarly, you can say my list.

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One is equal to B, you get through.

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So my list one and Z is the same value.

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So both these points to the same value.

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Now, how do we get the index of one object?

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Let's say we want to know the index of B.

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To do that, you need to use my list.

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That index a method and provide the object you want to know the index of and you'll get one.

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So that is the index of B.

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So index is listed in the list methods.

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If you scroll here, you'll see index.

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Now let's try this methods with underscores.

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So it has double underscores in the beginning.

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Double underscores at the end.

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All these methods with double underscores are actually used by Python internally we don't need to use

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them but what if we do?

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So let's try that.

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My list dot underscore, underscore, set, item, underscore, underscore with two parentheses.

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So this is the same syntax.

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As here.

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Now, this method takes two arguments.

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The first argument is an index.

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So let's try index one.

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Index one points to string B.

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The second argument is.

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The new value you want to set for the item with index one.

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So let's say.

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DX You press enter, you check my list and you'll see that DH has replaced B So that was the previous

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list.

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Now the list is updated so that there is the equivalent of saying my list one is equal to the new value.

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So let's try e this time.

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Now my list will be updated.

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So now DH is gone.

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E is the new item.

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So which one should you use?

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This or that?

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The short answer is use this.

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And actually when you use this, all the background, the interpreter actually calls the set item methods.

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So every changes that are done are being done by methods.

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But the Python code developers have been nice and they have provided this simpler syntax for very common

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methods such as setting an item.

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Similarly, there is also a get item.

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Methods.

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So my list does get item with double underscores.

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And let's try to this time I did a typo obviously so get.

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Item with one T and we get C, So the item with index two is C, and so that is the equivalent of try

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to guess it.

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Well this so you get See, my list stays the same.

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And this time.

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So in this case, we're not changing the list.

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Some methods such as set item, change the list and some other methods simply access some information

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from the list and they don't change the list itself.

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So that was a long video on code experiments, but plenty of information.

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So thanks a lot for following.

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See you.