[Python] 2. Expressions

Constants

- Fixed values such as numbers, letters, and strings, are called "constants" because their value does not change

- Numeric constants are as you expect -- 123, 34.1

- String constants use single quotes or double quotes --  ('), (")

 

Reserved Words

- You cannot use reserved words as variable names/ identifiers

Variables

- A variable is a named place in the memory where a programmer can store data and later retrieve the data using the variable "name"

- Programmers get to choose the names of the variables

- You can change the contents of a variable in a later statement

Python Variable Name Rules

Must start with a letter or underscore_
Must consist of letters, numbers, and underscores

Case Sensitive

 Sentences or Lines

*Recommend using a mnemonic variable name for human

 

Assignment Statement

We assign a value to a variable using the assignment statement(=)

An assignment statement consists of an expression on the right-hand side and a variable to store the result