Python Variables and Naming Rules

Study Notes

A variable is a named location in the computer's memory that holds data.
It's like a container for information that can be changed later in your program.
Mnemonic variables (those easy to remember and associated with their purpose); are recommended to use in programming.
Variables are declared and assigned values using the = operator. For example, number = 90.

Variable names must start with a letter (A-z) or an underscore (_).
Variable names cannot start with a number (0-9).
They can only contain alphanumeric characters and underscores.
They are case-sensitive (firstname, Firstname, FirstName, and FIRSTNAME are all distinct variables).
Lowercase letters are recommended for variable names.

Python developers use snake_case naming convention, where words are separated by underscores (e.g., first_name, last_name, engine_rotation_speed).

Think of a variable as a name attached to a particular object.
In Python, you don't need to explicitly declare the type of a variable, as Python is a type-inferred language.
Python automatically determines the type of a variable based on the assigned value.

website = "github.com" assigns the string "github.com" to the variable website.
first_name = 'Ron Marc' stores the string "Ron Marc" in the variable first_name.
number = 90 assigns the integer value 90 to the variable number.
Multiple variables can be declared and assigned values in one line using commas: a, b, c = 6, 9.3, "Hello".
Variables can be assigned values from within a dictionary, as in person_info = {'firstname':'Ron Marc', 'lastname':'Charles', 'country':'Philippines', 'city':'Makati'}

Python does not have built-in support for constants, which are values that should not change.
It's considered good practice to name constants in all uppercase letters (e.g., PI = 3.14159).
While there is no strong enforcement mechanism for constants, using uppercase naming conventions helps create code that's self-documenting and promotes consistency.

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