2.1. Introduction¶

This chapter introduces several basic building blocks of Python programs:

literals, like numbers and character strings
operators, like + and *
function calls, which take values as inputs and compute new values
variables, which save values so they can be used later in the program

These are the basic building blocks that are assembled to create programs that you interact with everyday—from the software running on your smartwatch, to the infrastructure behind the largest websites, and every app running on your phone.

2.1.1. Learning Goals¶

To understand Python’s storage model
To understand how to assign values to variables so they can be stored and reused
To understand operator precedence
To distinguish between expressions, values, and printed representations
To recognize & explain hard coding
To understand how to get input from an end user

2.1.2. Objectives¶

After completing the exercises in this chapter, you should be able to:

Given some sample code, identify variables that reference an object of a particular type
Given a variable of one type, convert it to another
Simulate evaluation of an expression and assignment statement
Use reassignment to increment a variable
Get input from a user and convert the input to the appropriate type
Identify the following types of values: strings, integers, floats, functions
Recognize valid vs. invalid variable names
Write an assignment statement
Update a reference diagram after reassignment