Overview of types and values

- [Male Voice] There are just a few fundamental data types in Python. Here in Komodo, I've opened a working copy of types.py from chapter three of the exercise files. You'll notice down here on line four, there's a variable X and it's assigned the value seven, the constant number seven. And you'll notice on line six, I print the type of the variable X. So type is a built-in function that prints the type of a value or variable.

And so when I save and run this you'll notice that it says that the type is class 'int'. That's the integer type. It's one of the built-in types. Python uses a form of dynamic typing sometimes called duck typing where the type of a value is determined by the value itself. In other words, if it walks like a duck, it's a duck. So if I change this value to say 7.0 and I save and run it, you see now it's class 'float'. So it's a floating point number.

And if I put that in quotes now it's a string and so if I save and run this it says class string. Str is the name of the built-in class for the string type in Python. If I change it to the word true with a capital T, save and run, now it's class 'bool' 'cause that's the Boolean type. And if I change it to none, again with a capital N, this is the built-in type for not a value.

And so it says class 'NoneType' which is the name of that type. So these are the fundamental built-in types. Python is designed to be extensible so it's easy to create your own types within its object system. And we'll cover these built-in types in more detail in the rest of this chapter.