Variables are the one of the fundamental building blocks of Python that are used to hold data in memory.
Variables have two components, name and type. The data in the variables can be referenced by their names. Type defines what type of data it stores.
Let's start by creating one.
Declaring a variable is incredibly simple in Python. Unlike in other programming languages, you do not need to specify the type of variable, it is done automatically for you.
Example of variable declaration looks like this:
name = "John Doe" x = 777 print(name) print(x)The above code block prints
John Doe 777
- A variable is declared and assigned a value using the assignment operator =
- Python treats bool as a special type of integer. Technically, True has a value of 1 and False has a value of 0.
string is a collection of zero or more characters. Strings are commonly
declared using single quotation marks, but you can also use double
- Python treats integer numbers and decimal numbers differently.
Variable Naming Rules
Here are the rules for what are valid Python variable names:
- The variable name must begin with a letter or underscore
- The variable name cannot begin with a number or symbol
- Throughout the entire variable name, it can only contain alpha-numeric characters with the only exception being underscores
With that in mind, here are some examples of valid Python variable names:
apples _apples _apples_
And here are examples of invalid Python variable names:
1apples app les $apples %apples
Python supports five standard data types. We've already seen two of them already, Numbers and String. Here is the entire list:
It is useful to know that you can get the type of a variable by using the
type method, like so:
Output of the code prints:
name = "John Doe" print(type(name)) print(name) pi = 3.1415926 print(type(pi)) print(pi) x = 777 print(type(x)) print(x) isSuccess = True print(type(
We'll get into lists, tuples, and dictionaries in later lessons.
<class 'str'> John Doe <class 'float'> 3.1415926 <class 'int'> 777 <class 'bool'> True