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In this lecture, I want to briefly describe the building types in to see Python and the Python and

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micro python and to explain why these are important.

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So first of all, you should know that Python contains a number of built-In data types.

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These are numbers, sequences, mappings, classis instances and exceptions for our purposes.

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The most important of those built in types are the metrics and sequences.

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So you can see information here about the types of numbers the python supports this integers, float's

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and complex numbers.

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And then these are the types of sequences, lists, tuples and ranges.

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And I've got another lecture where I talk more about the sequence types now for again, our purposes.

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And I'm not getting into the details here, but for our purposes, the important thing to remember about

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types is that you can only do certain operations only between types of the same kind.

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So, for example, you can only numerically add two numbers.

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You can't add one number of type E.A., for example, with a string.

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And speaking of strange, you can see that down here, a string or SDR is a type of text sequence or

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text sequence type of a closer look at this.

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You said that the string is just a sequence of Unicode code points, as they call it, but we can also

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call those characters just not ASCII characters, but Unicode code points.

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So on the other side here, just to compare C Python on the list with micro Python on the right, you

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see that in Python we have most of the same building types that you find in Python, but not all of

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them.

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Scroll to the top of the left side.

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So you can see that on the micro python side, we still have exceptions, but arrays, bytes, dictionaries,

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floating point numbers, integers, lists and strings and tuples.

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So these are the built in types there as well.

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Let's have a look at a couple of simple examples to see what happens if you try to create operations,

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if you try to operate between data types that are not compatible.

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So let's start with simple numbers.

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So let's say that we've got a couple of variables.

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And as you can see, they hold integers or least one feature of Python that is particularly friendly

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for new programmers is that you don't have to tell Python what kind of data you are storing in a variable.

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You don't need to be explicit about that.

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So in C, for example, to create an integer variable and store an integer to it, you would need to

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do something like that.

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A E.A. A equals one.

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So you need to start by declaring the type of the data that you're about to store in a new variable

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by Python doesn't require that it can make insurence and figure out on its own that this number here

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is a integer and therefore variable A contains an integer.

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Or you could say that variable C will contain a floating point number like that.

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All right.

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So now we've got to integers.

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We can do something like this and add them together and the answer is going to be three.

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Now imagine that we've got another variable.

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Let's call that C.

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And now instead of numerical one, it's called the string one.

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Like that.

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No problem.

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Python is going to accept this new assignment and a new variable, but then if we try to add bait,

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let's make that a to see, then we're getting an error message.

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And Thony is also going to bring up the assistant to try and help us to fix it.

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So obviously here, the error message, which actually comes from the Python interpreter, indicates

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that we try to use an operator sine plus against two data types that are not compatible.

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And T and String says it makes no sense trying to add an integer to a string.

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So in such a case, what we need to do is to use casting.

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So casting tells Python that we want to convert a data type of one kind into a terror type of another

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kind.

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Now, this type of casting may not always work, but in many cases it does.

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So in this case, if you want to really add integer one to string one, what we can do is to cast string

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one into an integer.

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And that is a compatible casting because as you can see, the contents of the string is really number

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one.

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So we can say a plus.

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I can t see.

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And there is all this, too.

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So we used the casting instruction and t to convert the string into an integer.

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This may not always work.

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So for example, if I've got the which is a combination of say a number and a letter and then I try

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to say plus I t.

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This is not going to work because in this case the cast instruction failed.

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There's no way for Python to know how to convert this string into a number.

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All right.

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Now, the opposite, of course, is also true.

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So let's say that we have to I'm going to go for new letters.

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Let's go for P equals hello with a space in the end and let's make the world and now let's add a D and

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you can see that Python knows that this is a string and that is a string as well.

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So now the plus operator, instead of numerically adding these two variables, it will concatenate them.

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You add them together and create one larger string.

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The combination of the two component strings.

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Now, if I tried to create a new variable, let's call it one.

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Obviously, this is a numerical integer.

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And then I'm trying to add E to F, then I'm getting a similar error message.

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Again, the system is telling me that I can't concatenate a string to an integer, which is basically

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the message that the interpreter is giving us directly right here.

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So how to do this again?

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We can use casting and we can say that I want it to be added to the string version of F or to the to

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the string casted version of numerical one.

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And that will give us a one.

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So, of course, you can do similar types of operations with other data types, but at this point I

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just want you to understand the differences between the various stereotypes and that often, but not

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always.

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It is possible to convert one data type to the other for more complex stereotypes, like, for example,

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for sequences.

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These are data types such as lists and dictionaries.

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Things are a little bit more complicated because you've got multiple elements.

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And in some cases, such as in a tuple, for example, that I've got a dedicated lecture about, things

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get even more interesting since a tuple is capable of containing multiple dark types so you can have

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a table that in it you can store numbers and strings, for example, and even arrays and things of that

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sort.

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The things that get a little bit more complicated.

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But again, with a little bit of planning ahead, it's impossible to program.